Cryptomelane-type manganese oxides octahedral molecular sieve (K-OMS-2) were used for the acid-catalyzed condensation of phenylhydroxylamine with aniline to produce 2-aminodiphenylamine. The H+-exchanged K-OMS-2 was found to be an efficient catalyst for this reaction. The reaction showed high selectivity (similar to 96%) for the ortho isomer of aminodiphenylamine compared with the para product. The effect of the amount of H+ exchange and temperature was investigated. (c) 2005 Elsevier Inc. All rights reserved.