This paper reports preparation and characterization of Ni/NiO nanocomposite using solid-state thermal decomposition method at 400, 500 and 600 °C from bis(N-(2-hydroxyphenyl)cinnamaldimine)nickel(II). Thermogravimetric analysis of the complex revealed its thermal stability and decomposition pattern. The as-prepared Ni/NiO nanocomposites were characterized by FT-IR, XRD, SEM and XRF. The XRD results confirmed that the composites were a mixture of Ni and NiO and also show upon increasing the temperature from 400 to 600 °C in air atmosphere; the amount of metallic Ni was found to decrease due to transformation to NiO. The SEM images confirmed that the Ni/NiO nanocomposites were almost similar morphology. XRF results show that the mass ratio between Ni and NiO prepared at 400, 500 and 600 °C is decreasing in order of 10:90, 8:92 and 4:96 %, respectively.