In this work, we present a systematic study of the transport properties of Ni80Fe20 nanowire arrays with varied film thicknesses. Closely packed nanowire arrays of width 185 nm and edge to edge of spacing 35 nm were fabricated using deep ultra-violet (DUV) lithography at 248 nm exposing wavelength. Our thickness-dependent study reveals a crossover from coherent rotation to curling mode of magnetization for t >= 80 nm. This is attributed to the spatially varying demagnetizing field across the wire. The magnetization reversal for fields applied along the hard-axis is mediated by coherent rotation, for all the thicknesses investigated. We also observed the appearance of exchange bias effect at 4 K, due to the formation of an anti-ferromagnetic phase. (c) 2005 Elsevier B.V. All rights reserved.