The splitting of [beta]-arylether bonds in phenolic lignin units (type A, scheme 1) by white liquor has been studied with appropriate model compounds and with some of the intermediates expected to be formed from these model compounds during the splitting reaction. The route for the synthesis of the intermediates (scheme 2) and their behaviour towards white liquor and 2 N sodium hydroxide support the mechanism suggested recently and outlined in scheme 1. This mechanism includes the incorporation of sulfhydryl groups into lignin and explains the important function of these groups in enhancing the alkaline cleavage of arylether linkages. In terms of the results obtained it is possible to interpret the favourable effect of the inorganic sulphide present in white liquor on the dissolution of lignin during sulphate cooking.