BACKGROUND: Revalorization of lignin is one of the key economical requirements for the development of cost-effective biorefinery processes. The lignin polyphenolic structure is ideally suited to transformation catalytically into lower molecular weight compounds such as phenols, aromatic acids, esters, ethers, etc., replacing those obtained from petroleum. RESULTS: Lignin was subjected to base catalyzed depolymerization paying attention to the base effect on the oil yield and composition. The oil yields and compositions varied (520%) strongly depending on the base used, suggesting that the reactions took place via different mechanisms. As a result, the monomeric compounds obtained were different (catechol, cresols, syringol, guaiacol). Residual lignin contents were high for most of the experiments (up to 45%), and repolymerization reactions were proved to be one of the main reasons for this behavior. CONCLUSION: The results showed that lignin depolymerization produced phenolic compounds that can be introduced into existing petrochemical industries. The base selection will govern the nature of the products obtained. Repolymerization was proved to take place and to be the reason for the limitation on oil production. Copyright (c) 2012 Society of Chemical Industry