The variational solution of the CH2OH nuclear problem was performed by treatment of CH2OH as a planar molecule with highly anharmonic vibrations. A sophisticated dynamic model to describe the structural flexibility of CH2OH was applied. The detailed analysis of the rovibrational Hamiltonian is shown. The electron problem solution was obtained by use of the coupled cluster electron correlation technique and the augmented correlation-consistent polarized basis sets of triple- and quadruple-zeta qualities. The geometry and energy parameters were extrapolated to the complete basis set limit. The partition functions of CH2OH were calculated by the explicit summation of vibrational and rotational levels. The heat of formation of CH2OH, Delta(f)Hdegrees(298.15 K)=-17.0+/-0.7 kJ/mol, was calculated by a study of the CH2OH-->CH2O+H reaction using the augmented basis set of quintuple-zeta quality and the relativistic and core-valence corrections of the total energies. Some structural and thermodynamic properties of CH2O are reported. (C) 2003 American Institute of Physics.