The feasibility of enhancing cross-linking in drawn polyethylene tape by a two-stage process involving first irradiation and second exposure to acetylene gas, has been established. A number of variables have been investigated; a dose of 50 kGy gamma irradiation in vacuum at -196-degrees-C followed by exposure to 1 atm acetylene for 36 h results in a cross-linked product with far superior creep performance to that of the untreated tape without loss of tensile modulus or strength. The treatment is particularly effective for the improvement of creep performance at 100-degrees-C. It is also shown to be slightly superior to both irradiation in vacuum and irradiation in an acetylene atmosphere, each under optimum conditions.