The electric field- current density (E-J) characteristics of a Nd-123 single crystal superconductor at different temperatures were estimated from a relaxation of magnetization. For the investigation of flux pinning characteristics of this superconductor, the E-J characteristics were analyzed and compared with theoretical calculations using flux creep-flow model. The pinning parameters such as Am, g2, σ2, m, γ, δ are determined so that a good fit is obtained between the experimental and the theoretical results. The Chittagong Univ. J. Sci. 43(1): 21-30, 2021