A model hydrocracking catalyst with a narrow and homogeneous distribution of mesopores of 3.2 nm of diameter has been prepared by alumination of the surface of a siliceous MCM-48 material, loaded with platinum and evaluated in the hydroconversion of n-hexadecane. Compared to zeolite catalysts featuring a similar acidity but containing both micropores and mesopores, the Pt/Al-MCM-48 catalyst leads to the same overall activity but with higher hexadecane isomer yields and a symmetrical repartition of the cracked products, typical for primary central cracking, even at very high conversion levels. It is suggested that the unique behavior of the model Pt/Al-MCM-48 mesoporous hydroconversion catalyst is due to optimal sorption energetics of the primary reaction products in the network of uniformly distributed mesopores. (C) 2015 Elsevier Inc. All rights reserved.