Iron ore reduction and carbon deposition under H2-CO mixtures were investigated by using the non-isothermal method. Iron ore in three different configurations were used in this work: pellet, coarse granularity particles and fine granularity particles. The reduced samples were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and accelerated surface area and porosimetry System(ASAP 2020M+C). In pure CO, the carbon deposition increases with decreasing of the sample size. In H2-CO mixtures, the rate of carbon deposition is accelerated dramatically. Morphologies of samples treated in different reducing ambinent were investigated. Specific surface area of the treated sample increases with higher level of carbon deposition.