The solubility of nitrogen in pure molybdenum was measured over the temperature range of 2173 to 2473 K and up to one atmosphere (101 kPa) of nitrogen gas pressure. Both thermochemical and kinetic aspects of this phenomenon were considered in this study. The solution of nitrogen in molybdenum may be expressed by the reaction $$1/2N_2 \left( g \right) = \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{N} \left( {Mo, s} \right)$$ , for which the standard Gibbs energy is given by the expression ΔGo = 78,500 + 27.367T Joules/g atom N. The formation of molybdenum nitrides, specifically, Mo2N, was considered. Attention was also focused on the mechanism of nitrogen solution in molybdenum. Estimates of the diffusivity of nitrogen atoms in solid molybdenum were derived from the kinetic data.