In this study, we investigated the oxidation of acetaldehyde over Co/carbon black catalysts. All experiments were conducted in the temperature range of 200-440 °C, at an acetaldehyde concentration of 0.94 mol% in air, and using Co loading amounts in the range of 2-60 wt%. The nanosized carbon black and Co/carbon black catalysts were characterized using thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analysis. The TGA data revealed that the nanosized carbon black was stable at high temperatures (600 °C), and the XRD results indicated that Co/carbon black was deteriorated and Co oxides, such as Co₃O₄, were formed. The addition of Co₃O₄ crystallites on the catalyst surface provided the greatest increase in catalytic activity. The catalytic activity of the supports used in this study for the acetaldehyde oxidation reaction increased as follows: SiO₂ < TiO₂ < carbon black < SiO₂-Al₂O₃. The experimental results and economic considerations revealed that nanosized carbon black could be effectively used as catalyst support for the oxidation of acetaldehyde. The activity of the Co/carbon black catalysts varied with the Co loading amount, and the optimum Co loading amount was 10 wt%.