The solubility in 1 per cent acetic acid solution of 8 types of limestones from the State of São Paulo, Brazil, was studied. A sample of pure calcite from the State of Go;ás, Brazil, was also included in these studies for comparative purposes. The chemical composition of these limestones is given in table 1. Samples a, b, and c were sedimentary limestones whereas samples d, e, f, g and h were metamorphic limestones. Two fractions of each limestone were separated, corresponding to Tyler sieve meshes 65-150 and 150-270. In order to study the effect of variations in sample weight per unit volume of solvent on solubility, samples weighing 250, 333, 500, 833, 1,250, and 2,500 mg were prepared from each of the two fractions of the different limestones, and shaken for 30 minutes with 250 ml of 1 per cent acetic acid solution. The results on solubility of the different samples, expressed as CaCO3 equivalent, are summarized in figures 1 and 2. They indicate that the limestones with a high content in CaO are more soluble than those with a high content in MgO. Within the group of dolomitic limestones, those of sedimentary origin were more soluble than the metamorphic ones. The influence of texture of the material on solubility was relatively greater for the metamorphic dolomitic limestones than for those with a high CaO content.