In this study, we report on the current-voltage characteristics of a bridge cut out from YBCO single crystal. The de-pinning critical current and the flux flow resistance dependencies on temperature have been investigated for samples placed in a zero magnet c field and in a magnetic field of 1.5 T applied parallel to the c-axis of the crystal (Hparallel toc). The overall observed general behavior is similar to the flux creep and flux flow behaviors that have been observed in "cold" superconductors. Down to 78 K, the glass-like e behavior of used crystals is absent. Between the irreversible and the shoulder temperatures, the existence of spatially inhomogeneous vortex phase is very plausible: solid phase-in the vicinity of twins and liquid-far from twin planes. Direct measurements of the shear modulus and plastic flow of vortex lattice were performed and included. (C) 2004 Elsevier B.V. All rights reserved.