High-pressure electrokinetic (“EK”) pumps comprising a hybrid monolith provide a high surface charge density and a continuous stable skeleton morphology with micrometer-sized through-pores. The hybrid monolith of the subject invention has superior mechanical strength and better stability in comparison to prior art monoliths with equivalent mechanical stability. The surface charge of the hybrid monolith can be modified and/or made stable by the use of different chemical reagents. The chemical reagents and resulting modification to the monolith serves to expand the usefulness of the hybrid monolith to a variety of pumping applications including chip-based systems and other applications where the ability to pump an acidic solution is required.