In this work, the thermal and mechanical properties such as coefficient of thermal expansion, strength, Young's modulus and fracture toughness of LaCoO3 and La0.8Ca0.2CoO3 perovskites have been studied, as well as slow crack growth of La0.8Ca0.2CoO3. The mechanical performance of the two cobaltites have been evaluated in terms of their ferroelastic hysteresis properties such as non-symmetry in bending of both stress and strain distributions, non-linear deformation upon applied load from the arbitrary low stresses, and ferroelastic toughening. (C) 2008 Elsevier B.V. All rights reserved.