Electronic spectra have been observed in the visible region for three 8-co-ordinated molybdenum cyanides containing one, two or three d-electrons. If the observed transitions are interpreted in terms of a dodekahedral crystal field, the dodekahedral Dq values come out in the order M05+(6214 cm−1) > M04+(5312 cm−1) > M03+(5728 cm−1). For M04+ one crystal field band has been found to show vibrational structure which could be represented in terms of two fundamental vibrations, 482 cm−1 and 346 cm−1. A tentative assignment has been made.