Cadmium Selenide (CdSe) micro/nanowires of different diameters were synthesized in polycarbonate membranes on copper substrate by template assisted electro-deposition method at room temperature. The structure, morphology, elemental, optical and electrical properties of CdSe micro/nanowires were investigated using X-ray Diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV–vis) spectroscopy, photoluminescence (PL) spectroscopy and probe station assisted with Keithley source meter. Structural analysis by X-ray diffraction depicted polycrystalline nature with hexagonal phase of micro/nanowires at all diameters. An increase in the value of average crystallite size was seen with increase in diameter. Morphological investigation confirmed the micro/nanowire synthesis and revealed an ordered array of prepared CdSe micro/nanowires of uniform diameters and having high aspect ratios. Optical band gap is found to increase from 1.89eV to 2.24eV as the diameter is decreased from 1µm to 50nm. Using the band gap values, refractive index and optical dielectric constants (static and high frequency) were also evaluated. The electrical conductivity of CdSe micro/nanowires varied from 21.58 × 102Ω−1m−1to 1.93 × 102Ω−1m−1 when diameter was decreased. These semiconducting micro/nanowires arrays of different diameters may have potential applications in future nanoscale based electronic and optoelectronic devices.