We attempted to grow CoxFe4-xN epitaxial thin films on SrTiO3(001) substrates by molecular beam epitaxy supplying solid Co and Fe and a radio frequency N-2 plasma, simultaneously. The composition ratio of Co/Fe in CoxFe4-xN was controlled by changing the weight ratio of Co to Fe flakes in the crucible of the Knudsen cell used. We confirmed epitaxial growth of CoxFe4-xN (0.4 < x < 2.9) thin films by reflection high-energy electron diffraction and theta-2 theta X-ray diffraction patterns. The in-plane lattice parameter of the CoxFe4-xN films was almost the same as the out-of-plane lattice parameter, and they decreased with increasing Co composition, following Vegard's law. (C) 2012 Elsevier B.V. All rights reserved.