The thermoreversible gelation of a triblock copolymer polystyrene-b-poly(ethylenelbutylene)-b-polystyrene in three paraffinic oils was studied. The paraffinic oils used (Norpar 12, Norpar 13 and Norpar 15) are selective solvents for the middle FEB block of the copolymer. The three oils are chemically similar and they only differ in the average carbon number. Thus the solvent influence on the sol-gel transition and on the mechanical properties of the gels was analysed. The sol-gel transition temperature increased with the copolymer concentration and the average carbon number of the paraffinic oil. The mechanical properties of the gels were examined through oscillatory sheer and compressive stress relaxation measurements. The concentration dependences of the elastic storage modulus were established, and were similar for the three paraffinic oils with exponents close to those expected for systems in good solvents (2.25) that possess a structure close to that of chemical networks. The relaxation rates observed were extremely high suggesting a considerable mobility in the gel over the measurement time. The relaxation rate increased as the oil carbon number decreased. The swelling behavior was also examined. All gels swelled significantly. The swelling equilibrium ratios varied linearly with the copolymer preparation concentration. The gels formed in Norpar 13 and Norpar 15 show a similar swelling behavior whereas the gels formed in Norpar 12 show a swelling capability markedly lower.