Adapting seasonal medicinal plants for human consumption and every day use, is one of the ultimate objectives for both pharmaceutical industry and traditional medicine. This work presents a thermo-kinetic study carried out in a forced convection solar dryer in order to establish the optimal conditions for drying and storing Marrubium vulgare L. leaves, which is an endemic plant of Morocco used for its medicinal properties. The aim was focused on the influence of different controllable and uncontrollable aero-thermal conditions (drying air temperature, air flow rate and air pressure) on the water loss of fresh Marrubium vulgare leaves. Drying kinetics are carried out at four drying air temperatures (50, 60, 70 and 80 degrees C), two air flow drying rates (150 and 300 m(3)/h), ambient temperature ranged from 26 to 37 degrees C and external relative humidity between 11 and 37%. During the experiments, the moisture content of the samples was reduced from 6.941 to 0.014% (dry basis) when the drying air temperature increases from 50 to 80 degrees C, this leads to a significant decrease in the drying time from 4 to 0.34 h. The experimental results were used to determine the characteristic drying curve. Several models in literature have been tested to describe the drying data. The drying air temperature is a determining factor influencing the drying kinetics of Marrubium vulgare leaves. The drying rate decreases in low drying air temperature. The Midilli-Kuck model was found to be the best fitting the drying curves in thin layer of Marrubium vulgare leaves. A value of 2938.46 kJ/kg was found as average activation energy, it expresses the drying air temperature effect on the diffusion coefficient. Total energy consumption showed a downward trend with increasing drying air temperature and an upward trend with increasing air flow rate. Any increment in the drying air temperature increases the energy efficiency while any increment in the air flow rate decreases this latter. Dried Marrubium vulgare leaves at 80 degrees C and 300 m(3)/h contain relatively high amounts of total phenols in comparison with other drying air temperatures.