Porous CaZrO3/MgAl2O4 composites were synthesized in air by pressureless reactive sintering of an equimolar mixture of dolomite (CaMg(CO3)(2)), monoclinic zirconia (m-ZrO2), and alpha-alumina powders, with a 0.5 wt% lithium fluoride additive. The reaction behavior of the mixed powders (with/without LiF additive) was studied using high-temperature X-ray diffraction. A bulk porous composite resulted from sintering at 1300 degreesC for 2 h (in a nearly closed container, so as to increase the LiF-doping effect), which consisted of fine grains (CaZrO3 and MgAl2O4, similar to0.5-1 mum) and well-grown idiomorphic ones (MgAl2O4 octahedra similar to 2-4 mum). The idiomorphic spinel grains were located around the inner walls of relatively large pores. The composite showed appreciably high bending strength (sigma(f) = 110 +/- 8 MPa for a porosity of 31%). The porous CaZrO3/MgAl2O4 composites can be applied as high-temperature filters and lightweight structural components.