This study presents a comprehensive, multi‑scale, real‑time‑capable modelling and control framework for high‑temperature proton exchange membrane (HT‑PEM) fuel cells targeting heavy‑duty vehicle applications, developed within the EU‑funded MEAsureD project [1]. At the component level, physics‑based reduced‑order cell and stack models are formulated and validated against polarization (U–I) curves of ion‑pair membranes (IPM) under varying operating conditions (pressure, temperature, and stoichiometric ratios). These models capture the coupled heat, mass, and charge transport phenomena and the associated electrochemical reactions within the membrane electrode assembly (MEA). The HT‑PEM formulation incorporates thermodynamic potential together with temperature‑dependent activation, ohmic, and gas‑phase transport losses, relying on gas‑phase species concentrations and temperature‑driven proton conductivity in the solid electrolyte to enable accurate and computationally efficient voltage prediction [2]. At the vehicle level, a heavy‑duty fuel cell electric vehicle (HDV) architecture for long‑haul trucking is developed using a multi‑physics system simulation platform [3] to analyse powertrain performance, hydrogen consumption, and thermal behaviour under representative real‑world driving conditions. A scalable, multi‑domain driveline model integrates the chassis, fuel cell system with balance of plant (BoP), thermal management, and electrical subsystems, enabling virtual validation and optimisation of the complete powertrain. Particular emphasis is placed on BoP control and thermal management to ensure robust operation under both nominal and high‑temperature ambient conditions. The proposed framework provides a foundation for efficient design and control development of HT‑PEM‑based heavy‑duty powertrains, supporting next‑generation zero‑emission transport solutions.