In this study, the effect of Mn site substitution of B on the structural, electrical and magnetocaloric properties of manganites was investigated. Polycrystalline manganites with the chemical composition La0.67Ca0.33Mn1-x,BxO3 (x = 0, 0. 1, 0.2 and 0.3) were prepared by the standard solid-state process. It was found that the magnetisation, the Curie temperature and the maximum value of the magnetic entropy change I AS. 1 decrease with increasing concentration of B. (C) 2007 Elsevier B.V. All rights reserved.