By using thermogravimetric analysis, the catalytic effect of ferric sulfate on the pyrolysis of residues from the cassava starch industry was studied.Thermogravimetric data were adjusted to the distributed activation energy model (DAEM) with two pseudo components.Calculated values for kinetic parameters of residues pyrolysis are into the reported range for other types of biomass.Ferric sulfate had a strong influence on the decomposition parameters of the second pseudocomponent of the DAEM, which is identified as lignin.