TG and DSC techniques proved useful in the study of the thermal properties of lithium stearate, lithium 12-hydroxystearate and related greases. Under an inert atmosphere, the stearates decompose into the oxalate prior to the formation of the carbonate. For the related greases, oil degradation-volatilization shows a discontinuity under ambient conditions, because of oxidation and carboxylic acid formation. The atmosphere and the concentration of the soap affect the chemical kinetics of thermal decomposition of the stearates and the greases.