Abstract
A series of perovskite‐type manganites, 
(Ln = lanthanoids or Y), were examined for their electrode‐catalytic activities to reduce oxygen in alkaline solution. Polarization experiments using gas diffusion‐type electrodes revealed that the catalytic activity differed significantly with a change in Ln, being in the order of 
. This order coincides with the decreasing order of the ionic radius of 
.