Abstract. This paper presents the free surface behaviour of liquid in a partially filled automotive fuel tank under uniformly accelerated motion. The liquid in the fuel tank is subjected to violent sloshing during sudden acceleration or stopping of the vehicle which will produce structural vibration and noise in the passenger compartment. To reduce this sloshing, baffles are used inside the tank. The objective of this work is to study the influence of vertical baffles and fill levels on free surface elevation of liquid in a partially filled fuel tank. The simulation of liquid free surface behaviour under uniform acceleration is done using ANSYS-FLUENT software. A numerical model is developed based on Volume of Fluid (VOF) technique to track the free surface motion of liquid. The explicit time discretization scheme is employed to solve the volume fraction equation. From the numerical analysis, amplitude of free surface elevation and slope of free surface are predicted. Experiments are carried out with transparent fuel tank, fabricated using glass fibre and epoxy resin. A uniform acceleration is applied to the tank and free surface displacements of liquid are captured using high speed camera. Also, an analytical model is formulated to find position of the free surface of liquid in a rectangular container subjected to uniform acceleration. The free surface profiles obtained from the simulations are compared with the experimental results.