Abstract: Braking system is one of the most critical parts in a vehicle, and one of the main components of this system is brake booster valve body which plays a significant role in safety standards of the vehicle. The working conditions under the hood of the vehicle necessitate the valve body to have some special properties. This component should have high mechanical strength and the ability to maintain this strength at elevated temperatures. On the other hand, lower weight and lower cost are always desirable in industries. The material selection for the valve body is very important and should satisfy the aforementioned requirements. In order to select the best material for a large number of alternatives considering many different criteria, multi criteria decision making (MCDM) methods are used in this study. The weighting of criteria is carried out by entropy and analytic hierarchy process (AHP) methods and a combination of these two techniques are used as the final weights. MOORA, TOPSIS and VIKOR methods are used in this paper for selecting the best material for braking booster valve body. The alternative materials were ranked using these methods and the results of the analysis were compared using Spearman's rank correlation. PET-gf35 (PET reinforced with 35 wt% glass fiber) was found to be the best material for the valve body. Owing to the desirability of the results, the results of this study can be used in automotive industry in order to enhance the material selection process.