Thank you, Jambunathan. I was exploring (defconst org-file-apps-defaults-cygwin   '((remote . emacs)     (t . "cygstart %s")     (system . "cygstart %s")     ("ps.gz"  . "gv %s")     ("eps.gz" . "gv %s")     ("dvi"    . "xdvi %s")     ("fig"    . "xfig %s"))) (defun org-default-apps () "Return the default applications for this operating system." (cond ((eq system-type 'darwin) org-file-apps-defaults-macosx) ((eq system-type 'cygwin) org-file-apps-defaults-cygwin)  ((eq system-type 'windows-nt) org-file-apps-defaults-windowsnt) (t org-file-apps-defaults-gnu)))And it works for me so far. Your code is more compact but an ad-hoc solution as well. It is worth to take into consideration. Thanks again. I suppose you would like to know I have also tweaked your directions about odt-mathml for cygwin: (setq org-latex-to-mathml-convert-command   "java -jar $(cygpath -pw %j) -unicode -force -df %o %I") (setq org-latex-to-mathml-jar-file "/home/user/tmp-odt/mathtoweb.jar") with great success (Java 1.7 update 25, mathtoweb 4.0.0). Miguel. Jambunathan K writes: >    (eval-after-load 'org >      '(when (eq system-type 'gnu/linux)                                 ^^^^^^^^^                                 ^^^^^^^^^                                 'cygwin >          (setcdr (assq 'system org-file-apps-defaults-gnu ) "cygstart %s") >          (setcdr (assq t org-file-apps-defaults-gnu ) "cygstart %s")))