(defun match-paren (arg) "Go to the matching parenthesis if on parenthesis otherwise insert %." (interactive "p") (cond ((looking-at "\\s\(") (forward-list 1) (backward-char 1)) ((looking-at "\\s\)") (forward-char 1) (backward-list 1)) (t (self-insert-command (or arg 1))))) (global-set-key "%" 'match-paren) ; however, now you have to press C-q % if you want to insert a % ; when the cursor is at a parenthesis