In relation to joining of silicon nitride ceramics to metal, an extensive experimental study of the reaction between Si3N4 and 25%Cr-20%Ni austenitic stainless steel was conducted. Reaction rates were determined by thermogravimetry (TG) and reaction products were examined by X-ray diffraction. Cr2N, CrN, Cr3Ni5Si2 and Fe3Si were produced under a nitrogen atmosphere. Fe5Si3 and FeSi also were produced under an argon atmosphere. The reaction products were analyzed according to thermodynamic considerations. The incubation period was found in TG curves and it was much shorter under a nitrogen atmosphere than under an argon atmosphere. The rates at early stages and late stages of reaction were given by linear and parabolic rate laws, respectively. Possible reaction mechanisms were proposed based on the results of the TG analysis.