diff --git a/src/components/views/rooms/MemberInfo.js b/src/components/views/rooms/MemberInfo.js
index 3c098b3d7a..8d9e5dfe39 100644
--- a/src/components/views/rooms/MemberInfo.js
+++ b/src/components/views/rooms/MemberInfo.js
@@ -45,6 +45,7 @@ import MultiInviter from "../../../utils/MultiInviter";
 import SettingsStore from "../../../settings/SettingsStore";
 import E2EIcon from "./E2EIcon";
 import AutoHideScrollbar from "../../structures/AutoHideScrollbar";
+import MatrixClientPeg from "../../../MatrixClientPeg";
 
 module.exports = withMatrixClient(React.createClass({
     displayName: 'MemberInfo',
@@ -61,6 +62,7 @@ module.exports = withMatrixClient(React.createClass({
                 ban: false,
                 mute: false,
                 modifyLevel: false,
+                synapseDeactivate: false,
             },
             muted: false,
             isTargetMod: false,
@@ -211,8 +213,8 @@ module.exports = withMatrixClient(React.createClass({
         }
     },
 
-    _updateStateForNewMember: function(member) {
-        const newState = this._calculateOpsPermissions(member);
+    _updateStateForNewMember: async function(member) {
+        const newState = await this._calculateOpsPermissions(member);
         newState.devicesLoading = true;
         newState.devices = null;
         this.setState(newState);
@@ -460,6 +462,25 @@ module.exports = withMatrixClient(React.createClass({
         });
     },
 
+    onSynapseDeactivate: function() {
+        const QuestionDialog = sdk.getComponent('views.dialogs.QuestionDialog');
+        Modal.createTrackedDialog('Synapse User Deactivation', '', QuestionDialog, {
+            title: _t("Deactivate user?"),
+            description:
+                <div>{ _t(
+                    "Deactivating this user will log them out and prevent them from logging back in. Additionally, " +
+                    "they will leave all the rooms they are in. This action cannot be reversed. Are you sure you want to " +
+                    "deactivate this user?"
+                ) }</div>,
+            button: _t("Deactivate user"),
+            danger: true,
+            onFinished: (accepted) => {
+                if (!accepted) return;
+                this.context.matrixClient.deactivateSynapseUser(this.props.member.userId);
+            },
+        });
+    },
+
     _applyPowerChange: function(roomId, target, powerLevel, powerLevelEvent) {
         this.setState({ updating: this.state.updating + 1 });
         this.props.matrixClient.setPowerLevel(roomId, target, parseInt(powerLevel), powerLevelEvent).then(
@@ -544,7 +565,7 @@ module.exports = withMatrixClient(React.createClass({
         });
     },
 
-    _calculateOpsPermissions: function(member) {
+    _calculateOpsPermissions: async function(member) {
         const defaultPerms = {
             can: {},
             muted: false,
@@ -560,7 +581,7 @@ module.exports = withMatrixClient(React.createClass({
 
         const them = member;
         return {
-            can: this._calculateCanPermissions(
+            can: await this._calculateCanPermissions(
                 me, them, powerLevels.getContent(),
             ),
             muted: this._isMuted(them, powerLevels.getContent()),
@@ -568,7 +589,7 @@ module.exports = withMatrixClient(React.createClass({
         };
     },
 
-    _calculateCanPermissions: function(me, them, powerLevels) {
+    _calculateCanPermissions: async function(me, them, powerLevels) {
         const isMe = me.userId === them.userId;
         const can = {
             kick: false,
@@ -577,6 +598,10 @@ module.exports = withMatrixClient(React.createClass({
             modifyLevel: false,
             modifyLevelMax: 0,
         };
+
+        // Calculate permissions for Synapse before doing the PL checks
+        can.synapseDeactivate = await this.context.matrixClient.isSynapseAdministrator();
+
         const canAffectUser = them.powerLevel < me.powerLevel || isMe;
         if (!canAffectUser) {
             //console.log("Cannot affect user: %s >= %s", them.powerLevel, me.powerLevel);
@@ -782,6 +807,7 @@ module.exports = withMatrixClient(React.createClass({
         let banButton;
         let muteButton;
         let giveModButton;
+        let synapseDeactivateButton;
         let spinner;
 
         if (this.props.member.userId !== this.props.matrixClient.credentials.userId) {
@@ -886,8 +912,19 @@ module.exports = withMatrixClient(React.createClass({
             </AccessibleButton>;
         }
 
+        // We don't need a perfect check here, just something to pass as "probably not our homeserver". If
+        // someone does figure out how to bypass this check the worst that happens is an error.
+        const sameHomeserver = this.props.member.userId.endsWith(`:${MatrixClientPeg.getHomeserverName()}`);
+        if (this.state.can.synapseDeactivate && sameHomeserver) {
+            synapseDeactivateButton = (
+                <AccessibleButton onClick={this.onSynapseDeactivate} className="mx_MemberInfo_field">
+                    {_t("Deactivate user")}
+                </AccessibleButton>
+            );
+        }
+
         let adminTools;
-        if (kickButton || banButton || muteButton || giveModButton) {
+        if (kickButton || banButton || muteButton || giveModButton || synapseDeactivateButton) {
             adminTools =
                 <div>
                     <h3>{ _t("Admin Tools") }</h3>
@@ -897,6 +934,7 @@ module.exports = withMatrixClient(React.createClass({
                         { kickButton }
                         { banButton }
                         { giveModButton }
+                        { synapseDeactivateButton }
                     </div>
                 </div>;
         }
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index 9ad20bf56c..12765de198 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -729,6 +729,9 @@
     "Demote": "Demote",
     "Failed to mute user": "Failed to mute user",
     "Failed to toggle moderator status": "Failed to toggle moderator status",
+    "Deactivate user?": "Deactivate user?",
+    "Deactivating this user will log them out and prevent them from logging back in. Additionally, they will leave all the rooms they are in. This action cannot be reversed. Are you sure you want to deactivate this user?": "Deactivating this user will log them out and prevent them from logging back in. Additionally, they will leave all the rooms they are in. This action cannot be reversed. Are you sure you want to deactivate this user?",
+    "Deactivate user": "Deactivate user",
     "Failed to change power level": "Failed to change power level",
     "You will not be able to undo this change as you are promoting the user to have the same power level as yourself.": "You will not be able to undo this change as you are promoting the user to have the same power level as yourself.",
     "No devices with registered encryption keys": "No devices with registered encryption keys",