Through a simple thermal treatment of precursor M-phosphate compounds such as Mstruvites NH4MPO4•6H2O (M = Mg, Ni, Ni-rich, NixCo1-x), simultaneously mesoporous and amorphous metal phosphate materials were synthesized. The temporal evolution of mesopores responsible for the high surface area was accompanied by a crystalline-amorphous phase transformation during degassing of volatile compounds, NH3 and H2O. Such thermally induced phase transformation was linked to the response in the coordination environment of Ni and Co 2+ and their structural reconfiguration in the solid compound. Here, Ni 2+ demonstrated a near-ideal centrosymmetric octahedral coordination sphere compared to a distorted one of Co 2+ . Mg-, Ni-and Ni-rich NiXCo1-x-struvites form amorphous phases during thermal treatment and evolve stable mesoporous frameworks. At first, near spherical micropores form and coalesce later to possibly more elongated mesopores. The condensation degree to mesoporous structures associated with surface area, pore size and pore shape is directly dependent on the complex amorphous structure. Consequently, no significant formation of mesopores occurred in Co-and Co-rich NixCo1-x-struvite after thermal treatment as these compounds exhibit several crystalline-crystalline phase transitions.