In order to investigate the ferromagnetic interaction in the alpha phase of 2’5’-dihydroxyphenyl nitronyl nitroxide (HQNN), semiempirical and ab initio molecular orbital calculations were carried out for several pair models of HQNN molecules extracted from the crystal structure. It was shown that the effective exchange interaction (J(ab)) for the nearest neighbor molecules is ferromagnetic, being in agreement with the experimental result. The hydroxyl groups and the methyl groups contribute to the ferromagnetic interaction in the a phase of HQNN crystal.