Rhodium(l) complexes of the type, [Rh(COD)CIL] (COD = 1,5-cyclooctadiene and L = Ph3PO, Ph3PS and Ph3PSe) have been synthesized. The complexes show higher efficiency as catalyst for carbonylation of methanol to acetic acid and methyl acetate at 130degreesC and 15 bar pressure than the industrially used species [Rh(CO)(2)I-2](-).