CdTe and HgCdTe can be grown directly on Si(100) substrates by molecular‐beam epitaxy. The layers grow in the (111)B orientation. Single domain films are always obtained on Si(100) 8° off toward [011], whereas single and double domain films were obtained on nominal Si(100). A possible reason for the formation of these domains is discussed based on a microscopic model of the CdTe/Si interface. The structural quality of the layers is determined by double crystal x‐ray rocking curves. The narrowest rocking curves are obtained on single‐domain films grown on nominal Si(100) substrates; a full width at half‐maximum (FWHM) of only 230 arcsec was measured, compared to 460 arcsec on the best layer with two domains. For HgCdTe layers grown on CdTe/Si, rocking curves with 110 arcsec FWHM were measured; these layers aren‐type with electron mobilities above 5×104cm2 V−1 s−1at 23 K for a Cd mol % of 26%.