A process for producing an ion-conducting membrane comprising a recombination catalyst-containing membrane layer. The membrane layer if fabricated from an ink comprising a stabilised dispersion of recombination catalyst nanoparticles. Also provided are ion-conducting membranes for electrochemical devices, such as fuel cells or water electrolysers, with a recombination catalyst-containing membrane layer comprising dispersed recombination catalyst nanoparticles, a nanoparticle stabilising agent, and an ion-conducting polymer.