A process is described for the contemporaneous preparation of mesitylene and durene, characterized in that mesitylene and durene are obtained exclusively starting from pseudo-cumene without the use of any further chemical compound, operating in continuous, at a temperature ranging from 210 to 400°C, at a pressure ranging from 1 to 50 bar, with a weight space velocity ranging from 0.1 to 20 hours -1 and in the presence of a catalyst based on crystalline metal-silicates in acid form. After the recovery of mesitylene and durene from the reaction raw product, some of the remaining components of the raw product itself are recycled and fed to the reactor together with the pseudo-cumene.