Different concentrations of polyvinylpyrrolidone (PVP) have been successfully employed to prepare high purity tetragonal cassiterite nanoparticles, and control the growth of particle size. The effect of PVP on the structural, morphological, size, composition, and optical properties of the prepared cassiterite nanoparticles has been investigated. It has been found that various characteristics of tetragonal cassiterite nanoparticles could be optimized by simply changing the values of PVP. The pure tetragonal cassiterite nanoparticles have been produced at the optimum calcination temperature. The XRD and SEM results indicated the structural and morphological properties of the tetragonal cassiterite nanoparticles, respectively. The particles' size and their distribution have been displayed by TEM images. The composition phase and the surface composition of the prepared samples have been evaluated via FTIR and XPS, respectively. The optical properties of the prepared tetragonal cassiterite nanoparticles have been studied using UV-vis and PL spectroscopy. Outcomes cassiterite nanoparticles are useful for antibacterial activity and application of solar energy. INDEX TERMS Cassiterite nanoparticles, polyvinylpyrrolidone, thermal treatment technique, energy applications.