Nanocrystalline ZnO thin films have been grown on glass substrates by thermal evaporation technique. The structural, morphological and optical properties of the thin film were investigated using X-ray diffraction, atomic force microscopy (AFM) and UV measurements respectively. The study revealed that ZnO nanoneedles consist of typical single crystalline ZnO with perfect needle shape and small surface roughness. The grown ZnO thin film was subsequently used to fabricate a metal-semiconductor-metal (MSM) ZnO photodiode with palladium (Pd) contact electrodes. The detector was successfully tested using the UV source operating at lambda = 365 nm. The photoresponsivity of the detector is estimated to be 0.14 A/W. The device is expected to be used as a sensitive UV detector. (C) 2010 Published by Elsevier B. V.