The Fourier-transform Raman (FT-Raman) and infrared (FT-IR) spectra of 2-nitro-tetraphenylporphyrin (2-NO2-TPP), nickel-2-nitro-tetraphenylporphyrin (Ni-2-NO2-TPP), zinc-2-nitro-tetraphenylporphyrin (Zn-2-NO2-TPP) and copper-2-nitro-tetraphenylporphyrin (Cu-2-NO2-TPP) were acquired for the first time and carefully assigned and discussed. The effects of a β-NO2 group and the influence of the central metal on the molecular symmetry and vibrational spectra of the porphyrin macrocycle were also examined. The bands at 1323–1339, 1516–1526 and 961–971 cm−1 were attributed to the symmetric and asymmetric stretching vibration of the NO2 group and to the stretching vibration of the CβN bond, respectively, which connects the NO2 group with the β-carbon of the porphyrin macrocycle. These bands can act as a marker to distinguish β-NO2 TPPs from other β-substituent TPPs. Cu-2-NO2-TPP has a C4ν molecular symmetry, which is different from those of Ni-2-NO2-TPP and Zn-2-NO2-TPP, i.e. D4h.