Epitaxial growth of CuAlSe2 has been performed on GaAs and GaP substrates by LP-MOCVD technique using cyclopentadienylcoppertriethylphosphine, trimethylaluminum, and dimethylselenium as respective Cu, Al, and Se precursors. Growth orientation of CuAlSe2 depends on the substrate orientation, i.e., the epitaxial layers are oriented toward the appropriate direction which has the smallest lattice mismatch. The carbon incorporation from trimethylaluminium has been reduced by increasing the growth temperature and by increasing the dimethylselenium molar flow rate. The carbon incorporation has also been reduced about one order of magnitude by using the new Al precursor, ethyldimethylaminealane. The epitaxial layers have shown red, broad photoluminescence at 77K.