Nanostructured CuO thin films were prepared by a simple chemical bath deposition method in the absence and presence of different surfactants. The obtained structures were characterised on the basis of x-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and UV–Vis spectral absorption. XRD and Raman studies pointed to the formation of a pure phase of monoclinic CuO. SEM studies revealed 1-D nanostructures of different orientations and aspect ratios. The presence of surfactants produced more uniform and oriented nanostructures. The samples were absorbing in the UV–Vis region demonstrating their potential application in photothermal systems. All the samples showed photocatalytic activity against methylene blue with different degradation efficiencies.