A catalytic cracking process is disclosed in which octane improvement is attained by the addition to conventional cracking catalysts of small amounts of additive catalyst comprising a class of zeolites characterized by a silica to alumina mole ratio greater than about 12 and a Constraint Index of about 1 to 12 bound in a matrix chosen such that the matrix component forms a thermodynamically favored compound with selected cations. Sustained catalytic activity is achieved by pre-exchanging the catalyst to a high level of selected cation loading. By extending the active life of the additive catalyst, markedly lower makeup catalyst addition rates are required.