A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminophosphate as catalyst was developed. High yields with excellent selectivity were obtained with a wide variety ofketones under mild reaction conditions. The catalyst had the advantages of ease of preparation, ease of handling, simple recovery, reusability, non toxicity, and being inexpensive.