Abstract: An inline fluid heater is disclosed, comprising: an inlet operable to receive a fluid to be heated; a substrate defining at least one conduit fluidly coupled with the inlet to receive the fluid; a positive thermal coefficient heater thermally coupled with the substrate and operable to heat the substrate to provide a heated fluid by heating the fluid within the at least one conduit; and an outlet fluidly coupled with the at least one conduit and operable to provide the heated fluid. In this way, a compact, cost-effective and efficient heater is provided which avoids the need for safety devices or safety circuits, as the positive thermal co-efficient heaters are self-limiting.