Summary An acrylic/alkyl acrylate co-polymer and a mixture of non-ionic surfactants (sorbitan monostearate and sorbitan monostearate(20)OE) were used to prepare o/w emulsions for cosmetic use. Formulations with optimal performances were obtained by selecting appropriate percentages of components through statistical procedures. The non-polymeric surfactants were seen to affect the stability and appearance of the emulsion, although they were used at low percentages (0.3-0.6%), and were seen to interact with the polymer in different ways. The influence of twelve w/o emulsifiers (alcohol-, glyceryl- and sorbitan-derivatives) on the emulsion was examined and models of stability and thixotropic module were calculated: the thixotropic behaviour of the emulsion depended on the structural characteristics of hydrophilic and hydrophobic moieties of the w/o surfactant molecule.