The use of colloidal material offers an interesting alternative to top down approaches for the realization of low cost infrared detectors. We demonstrate photoconduction in thin films of a colloidal material in the mid-infrared (up to 7μm), using HgTe colloidal quantum dots. Thin films of the colloidal quantum dots have a large absorption coefficient (>104 cm−1), and the photoconductive response is dramatically improved by encapsulating the nanoparticle into an inorganic matrix of As2S3. Such devices show fast response and large detectivity (>1010 jones) at temperatures above 200K.