Intermediates of the cobalt carbonyl-catalysed carbonylation of ortho-substituted benzyl halides were identified by IR, View the MathML source- and View the MathML source-NMR spectra. The molecular structures of the acyl-type derivatives 2-MeC6H4CH2C(O)Co(CO)3PPh3 and 2-PhC6H4CH2C(O)Co(CO)3PPh3 were determined by X-ray crystallography. Structural features of these complexes are discussed. Intermediates of the cobalt carbonyl-catalysed carbonylation of ortho-substituted benzyl halides were identified by IR, View the MathML source- and View the MathML source-NMR spectra. The molecular structures of the acyl-type derivatives 2-MeC6H4CH2C(O)Co(CO)3PPh3 and 2-PhC6H4CH2C(O)Co(CO)3PPh3 were determined by X-ray crystallography.