The effect of green Compact porosity on the combustion temperature and microstructure of the product formed by combustion synthesis was investigated. The Combustion temperature of the reactant first increased up to about 33% porosity and then decreased. The dendritic morphology of Ni₃Al intermetallic Compound was observed in the specimen produced with initial porosity of 33%, whereas typical polygonal grain structure was observed in specimen produced with initial porosity of 16%. The porosity and grain size of Ni₃Al product obtained with heating rate of 600℃/min in Ar atmosphere could be decreased by an application of uniaxial pressure during combustion. (Received October 19, 1992)