Index: lib/matplotlib/backend_bases.py
===================================================================
--- lib/matplotlib/backend_bases.py	(revision 8092)
+++ lib/matplotlib/backend_bases.py	(working copy)
@@ -1895,6 +1895,16 @@
                 ax.set_yscale('log')
                 ax.figure.canvas.draw()
 
+        elif event.key == 'k':
+            ax = event.inaxes
+            scalex = ax.get_xscale()
+            if scalex=='log':
+                ax.set_xscale('linear')
+                ax.figure.canvas.draw()
+            elif scalex=='linear':
+                ax.set_xscale('log')
+                ax.figure.canvas.draw()
+
         elif event.key is not None and (event.key.isdigit() and event.key!='0') or event.key=='a':
             # 'a' enables all axes
             if event.key!='a':