For a wide variety of applications, imaging infrared seeker allows new generation weapon systems to reach high performance in terms of accuracy, standoff capability, target/false target discrimination, target recognition, etc. In the design of the seeker, the detector is a key component because the global performance is strongly related to the detector's and also because it has a large impact on the opto-mechanical concept. Thanks to the use of state-of- the-art CMT 2D IRFPA, new generation imaging infrared seeker (IIS) has very high performance (sensitivity, resolution, number of pixels) as well as a simple opto-mechanical architecture. Thomson-CSF Missile Electronics Division (DEM) has designed, manufactured, and tested breadboards of IIS with the support of French MoD. These IIS are based on 2D IRFPA provided by Sofradir under DEM requirements. The IRFPA selected for this development is a 128 X 128 CMT IRCCD sensitive in the 3-5 micrometers waveband integrated in an operational dewar cooled by a Joule-Thomson cooler. In this paper, first a technical description of the IR detector is given, then the electronic set developed is described, and finally the measured main figures are given.