A comparison of the gasification performance of olive pomace, coal, petcoke and their binary and ternary blends was carried out by means of TGA (thermogravimetric analysis) coupled with mass spectrometry (MS). The thermochemical behavior of the raw materials was a function of their composition and inorganic content. Olive pomace had a low ash content, a high volatile content and a low moisture. Moreover, olive pomace presented the highest reactivity. On the other hand, olive pomace presented the highest H-2, CO, CO2, CH4 and NO emissions, while the highest SO2 release was obtained with petcoke, showing the output stream coming from the gasification of coal the highest H-2/CO ratio. The presence of olive pomace in the blends improved their reactivity, increased the H-2 release and the H-2/CO ratio, and decreased the CO yield. A synergistic effect was observed in the gasification of the binary blend of olive pomace and petcoke. On the contrary, the gasification of the binary blend of olive pomace and coal presented an antagonistic effect. In ternary blends, either ssynergistic or antagonistic effects were observed, which depended on raw materials ratios in the feed. Finally, the lower the olive pomace ratio in the blends, the higher the porosity of the remaining residue was.