The coating thickness is an important factor to evaluate the coating quality and determining the properties of the hot-dip aluminizing (HDA)coating. In the present work, a hot dipping pure aluminum (99%) on stainless steel (AISI 303) rods was carried out for different diameters of rods (8, 10 and 12mm) and different lengths (250 and 500 mm) at different aluminizing conditions of temperature and time. The dipping temperature was set to 700, 740, 780, 820 and 860℃ .The dipping time was set to 1, 2, 3,4 and 5 minutes. A response surface methodology (RSM) using a central composite rotatable design (CCD) for a 2³ factorial, with 5 central points and α = ±2 approach, based on the experimental data, was used to obtain the optimum modelto get the best thickness of coating and the best conditions of dipping. A 2nd polynomial model was obtained with a confiding percentage of 95%.Analysis of the experiments using RSM indicated that 807℃ and3minare optimum dipping conditions for hot-dip aluminizing process with corresponding thickness of coating layers of 134 μmto Al layer,62.9 μm to intermetallic compound (IMC) layer and 197μm to total coating layer.