A process for the preparation of a 4-aminodiphenyl amino derivative which comprises:(a) contacting a hydroxybenzene of the formula ##STR1## wherein R is hydroxyl or amino with an aniline compound of the formula ##STR2## wherein R.sub.1 represents hydrogen or an alkyl radical in the presence of a .gamma.-aluminum oxide containing catalyst; and(b) contacting the product from step (a) with ammonia in the presence of the same .gamma.-aluminum oxide containing catalyst used in step (a).