Gel matrix of the natural polymer starch has been employed as template for the preparation of ZnO nanocrystals via solution-solid technique. The template offers selective binding sites for Zn(II) under aqueous conditions. Controlled solvent-exchange, further isolation of solid product by microfiltration and drying, and subsequent removal of the template backbone enable the synthesis of spatially separated ZnO nanocrystals. The crystalline character and near narrow particle size distribution pattern have been confirmed through powder XRD measurements and TEM with SAED observation. The morphology, surface and optical properties of ZnO sample were characterized by SEM observation, BET-surface area, UV–Vis and PL spectra. The UV photocatalytic activity of ZnO nanocrystals was studied by analyzing the degradation of methylene blue in aqueous solution. The nanosized ZnO sample showed greater photocatalytic activity than commercial TiO2 (P25) photocatalysts. The size and shape factor seems to be of great importance in the observed photocatalytic performance.