The reduction behaviour of cobalt (Co) and undoped nickel oxide (NiO) under different atmospheres (hydrogen (H2) + nitrogen (20%, v/v) and carbon monoxide (CO) + nitrogen (40%, v/v)) have been investigated by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Co doped and undoped nickel oxide in both reductants proceed in one step reduction (NiO → Ni) without intermediate. TPR results also suggested that the addition Co metal into NiO, give different intensity to the peak. The reduction process of Co and undoped NiO accelerated almost completely reduced at T = 700 °C when H2 was used as a reductant. Meanwhile, XRD analysis indicated that NiO without Co composed better crystallite phases of NiO with higher intensity. © 2020 Trans Tech Publications Ltd, Switzerland.