The aim of this study was evaluate the drying of the lemon grass plant (Cymbopogon citratus Stapf) at different air temperatures (40 °C, 50 °C, 60 °C and 70 °C) to adjust the experimental data obtained with different mathematical models and assess the quality of the plant after drying. A completely randomized design (CRD) was used with three drying replications for each speed and temperature of the drying air. The essential oil content extracted from the dried plant at 0.8 m s-1 and 1.3 m s-1 with manual control system was not affected by the drying process; the temperature of the drying air had a negative influence on the levels of the essential oil of the plant; drying with automatic control decreased the essential oil content for all velocities studied compared to the fresh plant; increments in the temperature of the drying air significantly reduced drying time. The mathematical model of Two Terms is adequate to describe the drying process of lemon grass plant (Cymbopogon citratus Stapf); diffusion values increased with increasing temperature of the drying air, while the value of activation energy was 62.84 kJ mol-1.