Solid residues of different coals derivatized with various phosphorus reagents, followed by washing with organic solvents, were examined with P-31 MAS NMR. In an examination of coal desulfurization and deoxygenation, special attention was paid to Illinois No. 6 coal treated with n-Bu(3)P. In addition to residual n-Bu(3)P and n-Bu(3)PS remaining in the solid coal, evidence for two additional species, namely, n-Bu(3)PH(+) and [(coal)-C-O]3PO was adduced, Their chemical shifts are 34 +/- 2 and 2.5 +/- 0.5 ppm, respectively. The latter resonance was observed regardless of the coal treated and the phosphorus reagent employed.