The synthesis and characterization of triorganotin(IV) derivatives of two 4-acylpyrazol-5-ones(4-acetyl-5-one (HPMAP) and 4-benzoyl-5-one (HPMBP)) and of four 1-acylpyrazol-5-ones (1-acetyl-5-one (APzH), 1-(4'-nitrobenzoyl)-5-one (NPzH) and 1-salicyloyl-5-one (SPzH)) as well as those of diorganotin(IV) derivatives of the three 1-acylpyrazol-5-ones are reported. The X-ray crystal structure of tributyl(4-benzoylpyrazol-5-onato)tin(IV) monohydrate is also described.