Cation diffusion in (La,Ca)CrO3 was examined by two kinds of diffusion experiments : Sr(NO3)(2) solution applied experiment on the La0.75Ca0.25CrO3 surface and a diffusion couple experiment of La0.95Sr0.05CrO3 /La0.75Ca0.25CrO3, with secondary ion mass spectrometry (SIMS) analysis. The obtained bulk chemical interdiffusion coefficients for Ca-Sr from the two different experiments were almost on the same line in the temperature dependence plots, as follows:D-bulk (cm(2)s(-1)) = 2.66 x 10(-2).exp(- 318(kJ mol(-1))/RT) (1173-1673 K).The grain boundary chemical interdiffusion coefficients for Ca-Sr were obtained by the SIMS depth profiles with a new fitting equation, as follows:D-gb (sm(2)s(-1)) = 10.1.exp (- 261 (kJ mol(-1))/RT) (1173-1373 K).For the calculation of the grain boundary diffusion coefficient, the width of the grain boundary is assumed to be 1 nm. The diffusion coefficient for grain boundary interdiffusion of Ca-Sr is calculated to be five times higher than that for bulk diffusion at the same temperature. The grain boundary diffusion coefficient increased with the 0.66 power of p(O-2), which has a relationship with the valence change of Cr at the grain boundary.