Copper oxide (CuO) thin films have been deposited on glass and steel substrates but here work is done on steel substrate by novel aqueous based Reflux method whereas deposition of CuO thin film uses copper sulfate as copper ion source from an aqueous alkaline medium. The effects of copper ion concentration, temperature, and deposition time are studied for deposition of thin films. The CuO thin films are characterized by XRD, UV, SEM, and contact angle. The X‐Ray diffraction results reveal that CuO is monoclinic in nature. Optical band gap is observed from UV–visible spectrophotometer which is 1.9 eV. The surface morphological studies obtained from SEM micrograph show rice shape of exterior. While wettability test shows hydrophobic nature of CuO. This material characterization of CuO thin film clearly indicates that these films can be widely used in various applications such as gas sensor, transducers such as thermocouple to measure thermo e.m.f, solar cells, and super capacitor.