Embodiments of the present disclosure aim to provide a catalyst layer ensuring a high cell voltage and having both excellent robustness and sufficient endurance, and also to provide a process for producing the layer, a membrane electrode assembly and an electrochemical cell. The catalyst layer comprises two or more noble metal-containing layers, and a porous ceramic layer placed between the noble metal-containing layers. Further, in the catalyst layer, voids exist between the porous ceramic layer and the noble metal-containing layers.