The distributions of Cu2+, Mn2+, and Zn2+ diffusing in thin oriented clay films of water‐saturated montmorillonite, vermiculite, illite and kaolinite were obtained using a miniature probe attachment for an x‐ray emission spectrometer. Diffusion coefficients were calculated from these experimental distributions. Only small differences in the diffusion coefficients of Cu2+, Mn2+, and Zn2+ at comparable concentrations were found for a given clay. The range of diffusion coefficients for CuCl2 was 1.7 × 10‐7 cm2 sec‐1 at 0.01 meq/g of vermiculite clay to 52.1 × 10‐7 cm2 sec‐1 at 0.5 meq/g of kaolinite. The diffusion rates of copper, manganese, and zinc through the clay minerals were of the order: kaolinite > illite > montmorillonite >vermiculite. Some estimates of the diffusion coefficients in the liquid phase and in the adsorbed phase are given. The anions, Cl‐, NO3‐, SO42‐, and OAc‐ when diffusing with the cupric ion affected its diffusion rate. The order of diffusion coefficients at a concentration of 0.5 meq/g of montmorillonite clay were: CuCl2 > Cu(NO3)2 > CuSO4 > Cu(OAc)2; the respective diffusion coefficients were: 9.5, 8.3, 6.9, 2.7 × 10‐7 cm2 sec‐1.