Magnetization measurements were presented in this paper for the spinel solid solutions ZnxCd1-xCr2Se4 for x=0.35, 0.41 and 0.45. The Cr moment is 2.8µ_B/Cr where the magnetization saturates for fields up to 10 KOe at low temperature. The ferromagnetic scaling properties permit to determine the critical temperature Tc; and the critical exponents b, g and d . Whereas the compounds with x=0.35 and 0.41 exhibit exponents compatible with a 3D Heisenberg ferromagnetic model, a slight increase of b, g and decrease of d were round for x=0.45 The Kadanoff scaling law g =b(d - I) is satisfied by the experimental data. Using the mean field theory and the spin-wave theory at low temperature, the exchange integrals were calculated up to the third nearest neighbors (tnn).