Resonance Raman (RR) spectra of meso-monosubstituted derivatives of metallo-octaalkylporphyrins were measured in solution and in solid form and compared with those of the analogous unsubstituted complexes. For planar complexes: (2,5,8,12,18-pentamethyl-3,7,13,17-tetraethyl-porphyrinato)zinc(II), 1; (2,8,12,18-tetramethyl-3,7,13,17-tetraethyl-5-phenyl-porphyrinato)zinc(II), 2; (2,3,7,8,12,13,17,18-octaethyl-5-methyl-porphyrinato)copper(II), 3, appreciably large downshifts (9–13cm−1) of ν2 mode involving mainly CβCβ stretching vibrations were detected. This fact was explained by steric interactions of meso-substituents with adjacent β-ethyl groups resulting in the increase of β-ethyl substituents hyperconjugation with the a1u orbital antibonding for the CβCβ bonds. RR studies also indicate the absence of any significant electronic and kinematic effects of meso-substitution. In the case of (2,3,7,8,12,13,17,18-octaethyl-5-methyl-porphyrinato)Ni(II) (4), (2,5,8,12,18-pentamethyl-3,7,13,17-tetraethyl-porphyrinato)Ni(II) (5), and (3,5,7,12,17-pentamethyl-2,8,12,17-tetraethyl-porphyrinato)Ni(II) (6) complexes the substitution with a single methyl group at one of the methine-bridge carbon leads to the nonplanar distortion with a ruffled type structure. The degree of nonplanarity is modulated by the kind and ordering of alkyl groups on the pyrrole rings and increases in the series of porphyrins 6→5→4. The RR spectra of all meso-methylsubstituted Ni-porphyrins in solution show the evidence of the conformational heterogeneity because of the presence of conformers with various but close degree of the macrocycle distortion.