The present invention relates to a method for producing a heat exchanger. The heat exchanger comprising at least one heat conducting conduit for passage of a first medium and at least one block of an open cell porous medium for passage of a second medium. The method comprises providing at least one groove in the open cell porous medium. Thereafter, the porous medium is bent in a direction such that at least part of the grooves are opened and heat conducting conduits are applied in this at least one opened groove. Thereafter, the porous medium is rebend such that the heat conducting conduits are locked in said open cell porous medium.