Rh(TPP)I(CO) (TPP = tetraphenylporphyrin dianion) reacts with OR- (R = Me, Et) in CH2Cl2 under CO to yield Rh(TPP)(CH2Cl). The proposed mechanism includes displacement of I- by OR-, reductive elimination of aldehyde from Rh(TPP)(OR), and S(N)2 reaction between the resulting Rh(TPP)(-) and CH2Cl2. The molecular structure of Rh(TPP)(CH2Cl) reveals the shortest Rh-C bond (2.010(4) A) among the reported (chloromethyl)rhodium(III) complexes and an unusually large "saddle" distortion of the porphin core.