The infrared spectrum of N,N-dimethyldithiocarbamate complex of nickel(II) has been recorded in the range 2000–250 cm−1. Normal coordinate analyses have been made for nickel dimethyldithiocarbamate and nickel dimethyldiselenocarbamate complexes and their infrared spectra indexed. The frequency shifts observed on alkyl substitution have been discussed. The M—Se stretching frequency occurs about 100 cm−1 lower in the diselenocarbamate complex as compared to M—S frequency of the dithiocarbamate.