Mutations of the human skeletal muscle voltage-gated sodium channel Na_V 1.4 cause a variety of muscular disorders. The substitution R1448H is a well known mutation which causes cold-sensitive paramyotonia congenita. The biophysical and molecular mechanisms of this cold induced disease are not well understood. Therefore, we investigated the fast and slow gating parameters of WT and R1448H in a broad temperature range (5°C-30°C). The steady state parameters of activation and fast inactivation of the two isoforms are influenced in a similar way. All time constants of fast and slow gating transitions are influenced in the expected manner i.e. cooling slows all gating transitions down. The voltage dependence of the time constants in WT channels is represented by a bell-shaped curve. In contrast, mutation R1448H produces a curve with a minimum at intermediate voltages demonstrating a certain discontinuity in the voltage dependence of fast inactivation. Our measurements show a complex dependency of sodium channel gating on temperature and highlight the importance of position 1448 especially for close state inactivation.