Thermoplastic hoses, one of the most important functional components of umbilicals, are composed of inner liner, synthetic fibre reinforcement and outer sheath manufactured from thermoplastic material with protection against ozone and ultraviolet (UV) radiation. Polyamide 11 (PA11) and thermoplastic polyurethane (TPU) are generally specified for the sheaths, but other materials that meet the function can be used, as high density polyethylene (HDPE). Regardless of the polymer selected for the sheath manufacturing, they need to guarantee the hose lower layers integrity in an offshore environment due to constant sun exposure and to the maritime environment. The amount of works that studied and correlated the effects of the overlap of UV radiation and saline environment on PA11, TPU and HDPE materials is not large. So, the objective of this work was to compare the mechanical and thermal properties of PA11, TPU and HDPE, by thermal, spectroscopic, and tensile analysis before and after UV and salt spray aging, in order to reproduce a degradation mechanism similar to real life of the thermoplastic hoses and relate the thermomechanical behavior of the three materials after aging to evaluate the material which best suits the use of the sheath. The materials used to manufacture the samples in this study were obtained from unused hoses, extruded with commercial PA11, TPU and HDPE. The virgin sheaths were submitted to infrared (FTIR), thermogravimetric (TGA), derivative thermogravimetric (DTGA), differential scanning calorimetry (DSC) analysis and tensile test, to obtain the initial properties of the materials. Then the aging tests were carried out, which were developed in four cycles. The first cycle was UV aging for 720h of samples initially in the virgin condition (1st cycle: UV), the second cycle was salt spray aging for 720h of aged samples from the first cycle (2nd cycle: UV+NS), the third cycle was salt spray aging for 720h of samples initially in the virgin condition (3rd cycle: NS) and the fourth cycle was UV aging for 720h of aged samples from the third cycle (4th cycle: NS+UV). After the end of each aging cycle, the PA11, TPU and HDPE samples were submitted to the same analysis as the virgin samples for comparative purposes. In FTIR, all materials had a reduction in the intensity of the material characteristic peaks, associated with breaking chain bonds. In HDPE, there was an increase in the carbonyl index and in TPU, the formation of a new functional group (C=C stretching in alkenes), associated with oxidation of the polymeric chain, chain scission and possible crosslinking. Thermal tests showed an increase in the degradation temperature and a small change in the melting temperature of PA11 associated with plasticizer extraction; in HDPE and TPU, there was a decrease in the thermal stability of the materials after aging and no changes in the melting temperature were identified. In the tensile tests, a decrease in the modulus of elasticity was observed in PA11 and HDPE after aging, attributed to the process of scission of the polymeric chains and consequent decrease in molar mass, and in TPU, a tendency to increase tension in deformation of 300% was observed in the samples aged by UV+NS, NS and NS+UV and a tendency to increase tensile strength in samples aged by NS+UV, associated with competition between chain scission and crosslinking. From the results found in this study, it can be concluded that the material least affected by aging cycles in its chemical structure and thermally was PA11. Regarding the mechanical behavior, TPU suffered less influence in its properties compared to other materials.