The electroclinic effect, in a material having a first order SAto SC* transition, is studied using the half leaky guided mode geometry. Using an approximately 1 μm thick, homogeneously aligned cell, the voltage induced director twist is characterized at a few temperatures in the SAphase. The mean field theory readily explains the data recorded at low fields where a linear dependence on voltage is found. However, at higher fields, an unexpected saturation occurs which is most likely caused by the influence of strong surface anchoring forces.