Abstract: Hydrothermal synthesis of the first chromium-piperazinium phosphate, (C4N2H12)CrOH(HPO4)2·H2O, and their thermal and magnetic characterization is reported. Under inert atmosphere (nitrogen) the title compound retains carbonous species above 800 °C, while at higher temperatures the desorption of organic rests and the condensation of hydrogenphosphate groups, accompanied by the evacuation of phosphorus oxides, takes place (CrPO4 is the final product at 1200 °C). Under reactive-oxygen atmosphere the piperazine combustion reduces the thermal stability with the formation of CrPO4?Cr(PO3)3 mixtures at 1200 °C. The temperature dependence of the magnetic susceptibility presents a Curie?Weiss law, with an effective paramagnetic moment 3.66 ?B close to that expected for a Cr3+ ion, and no indication of long-range magnetic ordering has been detected down to 2 K.

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