Great differences in limestone sulphation behaviour were found depending on the characterization method used. A comparison of thermogravimetric and batch fluidized bed characterization methods was made using eight limestones. The limestone requirements predicted by a fluidized bed sulphur retention model were very different depending on the method and working conditions used to determine characterization parameters of the limestone. The comparisons made showed the need of characterization of sorbents by batch fluidized bed, working with a CO2 concentration of 10 vol %.