In the case of several formaldehyde derivatives, with importance in atmospheric and combustion chemistry, the currently available thermochemical values suffer from considerably large uncertainties. In this study a high-accuracy theoretical model chemistry has been used to provide accurate thermochemical data including heats of formation at 0 and 298 K and standard molar entropies at 298 K for CF2O, FCO, HFCO, HClCO, FClCO, HOCO, and NH2CO. For most of the thermochemical quantities studied here, this investigation delivers the best available estimate.