We report the structural and optical properties of the perovskite GdMn 1-xCoxO3 (x = 0-1.0) compounds. Far-infrared (FIR) and Raman spectroscopy measurements were carried out at room temperature. The FIR spectra show four vibration modes at ∼ 190, ∼ 250, ∼ 400, and ∼ 600 cm-1 that correspond to external, torsional, bending, and stretching modes, respectively. It was found that the FIR active vibration energies exhibit splitting and shifting as the Co doping level increases. The Raman spectra reveal that the most intense spectral feature in the GdMnO3 is at 612 cm-1, which shifts to higher and lower energies, depending on the Co doping level. © 2010 Elsevier B.V.