Development of ultrafine grained/nanostructure Bimodal copper alloy via cryogenic rolling process and evaluation of its properties In this study, pure copper was subjected to rolling at liquid nitrogen and room temperature. The main objective was optimization of strength and ductility of a commercial pure copper. For this purpose, parameters such as strain, temperature and time of annealing after cryorolling process was evaluated and optimized. Standard metallography practices as well as mechanical tests were performed on the samples. The tensile test indicated that tensile strength of 95 % sample were 410 Mpa and 245 Mpa for cryorolled and cold rolled at room temperature, respectively. Dislocation density was also calculated by MAUD method. It was revealed that in the case of cryorolling sample, it was almost 1000 times more than that of the one rolled at room temperature. The samples which were cryorolled to reductions of 85 and 95% were subsequently annealed based on a DTA test at temperatures from 300°C to 400°C. It was found that 95% cryorolling and 15 minutes holding at 350 degC after rolling led in the optimized properties. Ultimate tensile strength was increased to 350 Mpa (almost 145 Mpa more than that of the as received pure copper) while 25 % elongation to failure was achieved. Optical microscopy and also SEM studies for the mentioned sample showed presence of narrow annealing twins. In addition, an abnormal increase in hardness after annealing and increased micro strain microstructure during annealing at the above temperature confirmed the possibility of a bimodal microstructure generation. Failure to reduce the dislocation density and untwining reactions could be contributed to the above observation. Keywords : Cryorolling, pure copper, bimodal structure