Fuel cells utilize the chemical energy of liquid or gaseous fuels to generate electricity. As fuel cells extend their territory to include heavy-duty vehicles, new demands for proton conductors, a critical component of fuel cells, have emerged. A near-term need is ensuring the chemical and mechanical stability of proton exchange membranes to enable long lifetime vehicles. In the mid-term, achieving stable conductivity of proton conductors under hot (>100°C) and dynamic fuel cell operating conditions is desirable. In the long term, targeting high thermal stability and tolerance to water enables the utilization of high energy density liquid fuels that will increase pay-load space for heavy-duty vehicles. This article presents our perspective on these near-, mid-, and long-term targets for proton conductors of heavy-duty fuel cells. Display omitted Fuel cells are an attractive technology to power zero-emission vehicles. Compared with battery-powered vehicles, fuel cells offer fast fueling and adequate fuel storage for long-range applications. Heavy-duty fuel cell vehicles have strenuous requirements with the most challenging target being the development of fuel cells with the durability to return capital investment over a longer lifetime. Fuel cell operation under hot and dry conditions enables simpler, low-cost fuel cell systems through better heat and water management. Utilizing high energy density liquid fuels can also increase pay-load space and eliminate the need for an expensive hydrogen infrastructure. Advanced proton conductors that can resolve these issues associated with heavy-duty fuel cell applications are needed. Here, we present the progress and promising options in meeting near-, mid-, and long-term targets with respect to performance, durability, and technical readiness to stimulate research on proton conductors for heavy-duty fuel cell vehicles. Fuel cell technology is an attractive electrification platform for heavy-duty vehicles. As fuel cells expand their territory to include heavy-duty vehicles, new demands for proton conductors—a critical component of fuel cells—have emerged. This article summarizes the perspective of original equipment manufacturers on the research needs for heavy-duty fuel cell vehicle proton conductors in the near, mid, and long terms.