Detailed microstructural studies have been carried out on porous β-wollastonite (CaSiO3) ceramics with 40-60% of the theoretical density. Xonotlite (Ca6Si6O17(OH)2) was used as starting material, and the reaction and sintering behaviour were systematically examined in the range 800-1200 °C in air. Analysis of the mechanical properties showed that the strength degradation of β-wollastonite ceramics was certainly induced by the change of microstructure. Isothermal annealing at 1100 °C, however, did not preferentially affect the microstructure or the mechanical properties of sintered β-wollastonite. These observations lead to the conclusion that the measured bending strength and Vickers hardness of porous β-wollastonite ceramics can be substantially modified and improved by controlling the microstructure, in particular due to the shape of randomly oriented grains in the matrix.