The SMP-buffer method for the determination of lime requirement was studied with 23 soil samples of the State of São Paulo. The method was calibrated against lime requirements to increase pH values to 5.5, 6.0 and 6.5 based on CaCO3 neutralization curves of the soils. A modification of the ratio of SMP-buffer to soil, which gives lower lime requirements per unit of pH depression is suggested for the use of soils that have rather low buffer capacities. The method proved to be satisfactory to predict amounts of lime needed to increase soil pH to values of 6.5, 6.0 and 5.5. Neutralization of aluminum, using a factor 1.5, increases the pH of the soils to values around 5.5.