The EC 635 Military version of the EC 155 mockup was a conversion of first preproduction EC 135 (D-HECX). Offered (unsuccessfully) to South Africa and unveiled at Aerospace Africa Air Show on 28 April 1998. First customer was Portuguese Army, which ordered nine EC 635T1s on 22 October 1999 for delivery from June 2001. However, these retrospectively cancelled on 14 August 2002, following delay in post-delivery modifications; all sold to Jordan which, in March 2003, increased its order to 16.
The EC 635 underwent testing with FN Herstal HMP 400 12.7mm machine gun, Giat NC621 20mm gun and 12-round 70mm rocket launcher.
EC-635 D-HECM (c/n 0529), the first of the type for the Swiss Air force, first flew, from the Donauwörth facility in Germany, on 23 May 2007.