The new gaseous species OMnF and OMnF2 were identified and studied by high-temperature Knudsen Cell Mass Spectrometry. Their thermochemical atomization energies were derived through the study of several all-gas equilibria in the temperature range 1735-1913 K. FTIR matrix isolation experiments together with ab initio and density functional calculations were performed to determine the molecular parameters, bond distances, and vibrational frequencies of OMnF(g) and OMnF2(g). The results allowed us to evaluate a set of thermal functions for the new species that were used in the evaluation of the equilibrium data. The proposed atomization energies and enthalpies of formation are Delta(a)H(0)(o)(OMnF,g)=(903+/-5) kJ mol(-1), Delta(f)H(298.15)(o)(OMnF,g)=(-297+/-5)kJ mol(-1), and Delta(a)H(0)(o)(OMnF2,g)=(1470+/-70) kJ mol(-1), Delta(f)H(298.15)(o)(OMnF2,g)=(-789+/-70)kJ mol(-1). (C) 2002 American Institute of Physics.