Vaporization of tin(II) pyrophosphate is studied by high-temperature mass spectrometry. Under neutral conditions, Sn₂P₂O₇ vaporizes congruently with dissociation. Molecules of SnPO₃ and SnPO₂ are detected in the vapor; their standard heats of formation are determined as -601 ± 3 and -312.0 ± 1.5 kJ mol^-1 (at 0 K), respectively.