(Ti, W, Mo, V)(C, N) powders were synthesized by carbothermal reduction–nitridation in an open system. Effect of NH 4 HCO 3 addition on the phase composition and microstructure of the synthesized powders were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that NH 4 HCO 3 addition plays a facilitating role in preparation of high-purity (Ti, W, Mo, V)(C, N) powders. With the temperature increasing, the residual carbon content decreases in the products but the nitrogen content is more stable. It is found that the morphologies of the synthesized powders exhibit high-porosity structure when NH 4 HCO 3 additive is added.