In this work, nanostructured NiSe thin films were prepared by the chemical solution deposition method at different pH fixing the deposition time. The surface morphology, structural and semiconductor properties of such films were investigated utilizing different methodologies. It was found that slight changes in pH can influence the optical bandgap and structure of NiSe films. The results of Tauc´s plot and the derivation of the ineffective thickness method were compared to estimate the optical bandgap energy and the transition index. Additionally, the Urbach energy was also assessed. The potential of the NiSe nanostructured samples as photocatalysts was evaluated by analyzing the decomposition of azoic Congo red dye under visible light radiation