There is disclosed a fluid supply manifold for use with various surgical instruments, such as, electrosurgical instruments. The fluid supply manifold includes two or more connection ports for receipt of sources of fluid supply by either bulk sources or sources contained within canisters. The manifold may include a mixing chamber for mixing the various sources of fluids within the manifold or may include flow tubes for providing the sources of fluid directly to the surgical instrument to be mixed within the surgical instrument. Control valves are associated with each of the connection ports to control the flow of fluids through the manifold. The manifold may also include a gas inlet to facilitate drawing the fluids out of the various sources as well as mixing the fluids within the manifold.