Natural rubber is the most common material for dynamic applications. Its limited service temperature leads to search alternative elastomeric materials for related areas. In this study, natural rubber, traditional ethylene propylene diene rubber (EPDM), and a new grade EPDM with modified structural properties have been evaluated by means of tensile properties, characteristic temperatures, cross-link density, isothermal and nonisothermal relaxation behaviors with temperature scanning stress relaxation (TSSR) method. Linear molecular structure of the alternative EPDM elastomers provided improved tensile strength and isothermal stress relaxation behavior. Small amount of process oil addition also improved their service temperatures due to better processing conditions. Annealing study showed that strain-induced crystallization is one of the important factors controlling service conditions of EPDM. Besides, TSSR technique was concluded to be a fast and powerful technique for measuring cross-link density and for predicting service temperatures of natural rubber and EPDM elastomers.