The microstructure and mechanical property of a commercial pure aluminum (1050) processed by equal channel angular pressing (ECAP) at cryogenic temperature, to an equivalent strain up to 8, was studied by hardness testing and transmission electron microscopy (TEM). The results show that the dynamic recovery is restrained partially by ECAP at cryogenic temperature (cryoECAP). High density dislocations still can be observed inside some grains after eight cryoECAP passes, which obviously differs from the microstructure produced by ECAP at room temperature (RT-RCAP). The peak hardness of cryoECAPed pure aluminum is 28% higher than that of room temperature ECAPed pure aluminum. © 2008 Elsevier B.V. All rights reserved.