Index: amsopn.el
===================================================================
RCS file: /sources/auctex/auctex/style/amsopn.el,v
retrieving revision 1.4
diff -u -u -r1.4 amsopn.el
--- amsopn.el	23 Oct 2005 10:13:01 -0000	1.4
+++ amsopn.el	28 Feb 2013 14:02:24 -0000
@@ -11,7 +11,13 @@
      '("DeclareMathOperator"  "Operator (with \\)" "Text")
      '("DeclareMathOperator*" "Operator (with \\)" "Text")
      '("operatorname" t)
-     '("operatorname*" t)))))
+     '("operatorname*" t))
+
+    (setq LaTeX-auto-regexp-list
+          (append
+           '(("\\\\DeclareMathOperator{?\\\\\\([A-Za-z]+\\)}?"
+             1 TeX-auto-symbol))
+           LaTeX-auto-regexp-list)))))
 
 (defvar LaTeX-amsopn-package-options '("namelimits" "nonamelimits")
   "Package options for the amsopn package.")