The performances of a multifunctional reactor based on the in situ condensation and separation of the product are investigated for two industrial importance exothermal catalytic synthesis: the benzene hydrogenation into cyclohexane and methanol synthesis from syngas. The condensed product is separated in situ from the reacting medium through a hydraulic seal, in order to drive the equilibrium composition towards the product. The experimental background for the reactor-condenser (axial and radial configurations) is presented. A one-dimensional, steady-state model is developed. The performances of the reactor-condenser are compared to industrial data in the case of the methanol synthesis. (C) 2003 Elsevier B.V. All rights reserved.