Superplastic behavior of ECAE processed ZK60 was examined at a temperature of 473 K. The grains were equiaxed with a fine grain size of 1.4 mum at the tensile testing temperature. It was found that this material exhibited superplasticity even at a low temperature of 473 K. The maximum elongation of 1083 % was obtained at 1x10(-5) s(-1). The apparent strain rate sensitivity value exhibited about 0.5 in the low strain rate range and remained unchanged during deformation, indicative of no change in grain boundary structure. The normalized plot indicated that the present material behaved almost identically to those with equilibrium grain boundaries. It was suggested that the present ECAE processed ZK60 alloy have the equilibrium grain boundaries at the superplastic temperature in contrast to typical materials processed by severe plastic deformation.