We report a study of magnetocaloric effect (MCE) in cyanido-bridged molecular compounds where M = Ni, Mn, pyrazole =. The substances show a sharp phase transition to a long range magnetically ordered state, with ferromagnetic coupling between M and Nb sublattices in the case of the Ni-based sample 1 ( = 13.4 K) and ferrimagnetic coupling for the Mn-based sample 2 ( = 23.8 K). The magnetic entropy change S due to applied field change H as a function of temperature was determined by the magnetization and heat capacity measurements. The maximum value of S at H = 5 T is 6.1 J mol K (5.9 J kg K$^{-1} ^{-1}$ K (6.5 J kg K) for 2 at T = 25 K. MCE data at different applied fields have been presented as one universal curve, which confirms magnetic transitions in 1 and 2 to be of second order. The temperature dependences of the n exponent characterizing the dependence of S on H have been obtained. The n() values, consistent with the shape of the magnetization curves, pointed to the 3D Heisenberg behaviour for 2 and some anisotropy, probably of the XY type, for 1. The dependence of the maximum entropy change has been tested in the ferrimagnetic series.