A set of experiments was carried out for validating a 40 cm long and 1/2 inch diameter sulphonation falling film reactor for the sulphonation of hydrogenated palm stearine-derived dodecylbenzene (DDB) and methyl esters (ME) compared to oleum-derived gaseous SO . Volumetric titration was used for determining the percentages of sulphonated (active) matter, sulphuric acid content and unsulphonated oil by petroleum ether extraction. The reactor's functionality was tested in the conditions reported by Gutiérrez et al., for DDB sulphonation. The falling film reactor analysis techniques applied to sulphonated DDB in the scale bank reactor were thus validated in Universidad Nacional de Colombia's Chemical Engineering Department Laboratory with the involvement of the Química Básica Colombiana Company (LIQ, Caloto, Cauca, Colombia). The influence of different process variables on the sulphonation of a mixture of methyl esters was then evaluated. The results obtained in the sulphonator were adjusted to empirical equations using multiple linear regression; these expressions showed the direct effect on sulphonation of variables such as SO /ME molar ratio, SO concentration in gas flow and ME mass flow. 3 3 3