The gasification reactivity of the chars from both raw and torrefied wood, grape marc, and macroalgae has been investigated in this paper. The variations in char gasification reactivity were explained using further investigation of the physicochemical characteristics of the char that can influence the gasification reactivity, i.e., specific surface area, uniformity of the carbonaceous structure, and concentration of alkali metals (Na and K). It was found that the influence of the torrefaction process on the char gasification reactivity strongly depends upon the solid fuel properties and pyrolysis conditions. For a pyrolysis temperature of 800 degrees C, the gasification reactivity of the chars from both the torrefied grape marc and the torrefied macroalgae was lower than that of the chars from their corresponding raw fuels. This is mainly due to a lower specific surface area and a lower content of alkali metals (Na and/or K) in the chars produced from both the torrefied grape marc and the torrefied macroalgae than for those chars produced from their corresponding raw fuels. However, the opposite influence of torrefaction was found for the macroalgae char when the pyrolysis temperature was increased to 1000 degrees C. This is attributed mostly to the higher Na content and the more amorphous carbonaceous structure for the torrefied macroalgae char than for the raw macroalgae char.