Recent proposals for high-current cw proton accelerators acknowledge the importance of superconducting technology for cost-efficient and reliable operation. Los Alamos National Laboratory is working on the design of a facility that accelerates a 100mA proton beam to a final energy of 1.7GeV. In our design, using 5-cell superconducting cavities for the major part of the accelerator requires delivery of up to 420kW of rf power into a single cavity. Presently used power couplers, in operation with beam, have never been used in this power regime. Our choice of using two couplers per cavity allows us to reduce the required level to 210kW, a reasonable extension of today’s operation experience. This is a report of the design choices we made, our design effort using state-of-the-art electromagnetic modeling tools, and of low power tests we did on a few of the coupler components.