Nanocrystalline 70 wt. % Ni–30 wt.% Fe alloy powders were synthesized by spray pyrolysis from a solution of nickelcene (C2H5)2Ni and ferrocene (C2N5)2Fe dissolved in 2-methoxyethanol. The alloy powder consisted of <10 nm and 70 to 80 nm particles. Thermodynamic analysis is shown to be a useful tool for gaining insight into the thermochemistry of the spray pyrolysis process.