A new method for the determination of sulfate in tobacco is presented. It consists of : dry ashing of tobacco, dissolution of ashes in water, precipitation of sulfate as baryum sulfate in acidic solution, complexation of free baryum with methylthymol blue in basic solution and colorimetric determination of free methylthymol blue at 460 nm, which is proportional to the sulfate rate in tobacco. This method is compared with the indirect determination of sulfate by atomic spectroscopy determination of baryum in the solution after precipitation of baryum sulfate. The colorimetric method is easier, faster, cheaper and the precision is similar. The authors practice the colorimetric method on a reference sample of tobacco and find a result close to the mean value and included in the confidence interval.