Abstract In the preparation of piezoelectric composites from an inorganic glass and calcium modified lead titanate ceramics, the anomalous thermal expansion in the ceramic on cooling from the para-ferroelectric transition, may cause mechanical stresses in the phases and their fracture. A combination of the Knoop and Vickers indentation techniques is here applied to the mechanical characterization of the component phases, which is of primary interest for the piezoelectric composite preparation. Values of Knoop and Vickers hardness and Young's modulus are obtained for PTC ceramics with molar ratios Ca/Pb=24/76 and 35/65 and for boron glasses. The variation of the crack to indentation sizes ratio in the Vickers test with respect to the applied load has been studied. This leads to the conclusion that in ceramics there is a transitional regime of crack development, whereas in glasses a median regime prevails. These results allow us to select the method for the calculation of the toughness, Kic, and internal stresses of these materials.