Swelling soils are cohesive materials capable of experiencing large volume changes linked to variation of its moisture content. Campo de Calatrava is an area of Ciudad Real province, Spain, where this kind of soils can be found due to the weathering of volcanic deposits generated during the Neogene. They have been seldomly studied due to the lack of population in the area and the moderate swelling potential compared to more expansive materials that can be found in other zones of the Iberian Peninsula. This study presents a new dataset of laboratory testing results not previously published based on swelling pressure at constant volume on oedometer apparatus. This additional data obtained mostly from site investigations for building construction has been integrated with the available geotechnical data on the literature to provide valuable observations (but preliminary at this stage; additional research is forthcoming) about the expansivity of Campo de Calatrava soils and their index properties.