Lactic acid is one of the most important compounds in the field of bio-renewable chemicals. Lactic acid is present in nature but can also be produced by chemical synthesis or by fermentation of biomass. It can be used as raw material for the production of biodegradable and environmentally friendly polymers or copolymers, such as poly lactic acid (PLA). In this work, the equilibrium distribution of monomer and low molecular weight oligomers of lactic acid in aqueous solutions at different overall concentrations of lactic acid (from 0.09 g/g to 0.94 g/g) and temperatures (423 K and 453 K), was investigated. In addition, a kinetic study of monomer and oligomer esterification reactions, of a lactic acid aqueous solution at about 0.09 g/g, was carried out at 423, 433, 443, and 453 K. The values of the kinetic constants were successfully correlated through Arrhenius' law.