An efficient membrane-based process for deacidification of lampante olive oil was investigated. The neutralization of the free fatty acids with appropriate soda concentration allows the formation of submicronic particles which are subsequently removed by a microfiltration technique. A total or quasi-complete neutralisation of the acidity is necessary to achieve the complete retention of the soap molecules. Partial neutralization of the acidity leads to a lower membrane separation efficiency. The residual FFA causes permeation of soap molecules across the membrane. When filtered under suitable conditions, lampante olive oils show excellent quality characteristics, i.e., very low residual acidity as well as soap and water contents. The initial fluxes, obtained during crossflow filtration with membrane pore sizes 0.5 and 0.8 [mu]m (147 and 212 1/h m2, respectively) after neutralization with 20% NaOH are twice those obtained with 40% NaOH while there is only a slight improvement with the 0.2 [mu]m membrane. The filtered oils show good quality (acidity and residual soaps) in the case of PS 0.2 and 0.5 gm, whereas the 0.8 [mu]m membrane allows some soaps to pass through the membrane. The passage from the laboratory scale (1 kg) to a 50 kg unit shows the practical possibility of scaling up without meeting any particular problems or loss of efficiency.