Bis(triphenylphosphine)silver(I) formate and its diformic acid adduct, [(PPh(3))(2)AgO2CH]. 2CHO(2)H have been prepared and characterized by infrared spectroscopy, solid state CP MAS C-13 and P-31 NMR spectroscopy, and single-crystal X-ray diffraction. Crystals of [(PPh(3))(2)AgO2CH] are isomorphous, with [(PPh(3))(2)CuO2CH] crystallizing as discrete monomeric units in the monoclinic space group C?Jc with a 2-fold crystallographic axis of symmetry through the bisector of the P-Ag-P angle and the anion. The formate anion is symmetrically coordinated to the silver with an Ag-O distance of 2.425(3) Angstrom. The Ag-P distance is 2.4261(7) Angstrom, and the P-Ag-P angle 127.37(3)degrees. Crystals of the diformic acid adduct belong to the orthorhombic space group Pnma, in which the PPh(3) ligands are related by a crystallographic mirror plane containing the silver atom, the formate anions, and the two molecules of formic acid. The anion is unsymmetrically coordinated with the Ag-O distances of 2.550(7) and 2.713(8) Angstrom, seemingly a consequence of strong hydrogen bond formation with each of the formic acid molecules, with 0 ... 0 distances of 2.56(1) and 2.50(1) Angstrom. Although the Ag-P distance of 2.426(2) Angstrom is unchanged from that of [(PPh(3))(2)AgO2CH], the P-Ag-P angle increases to 147.86(7)degrees, the largest yet recorded for the [(PPh(3))(2)Ag](+) cation.