Porous Al2O3/20 vol% LaPO4 and Al2O3/20 vol% CePO4 composites with very narrow pore-size distribution at around 200 nm have been successfully synthesized by reactive sintering at 1100 degrees C for 2 h from RE2(CO3)(3)center dot xH(2)O (RE = La or Ce), Al(H2PO4)(3) and Al2O3 with LiF additive. Similar to the previously reported UPC-3Ds (uniformly porous composites with a three-dimensional network structure, e.g. CaZrO3/MgO system), decomposed gases in the starting materials formed a homogeneous open porous structure with a porosity of similar to 40%. X-ray diffraction, P-31 magic-angle spinning nuclear magnetic resonance, scanning electron microscopy, and mercury porosimetry revealed the structure of the porous composites.