The invention pertains to a process for preparing a succinic acid ester comprising the steps of bringing an aqueous liquid comprising succinic acid, alcohol, and at least 5 wt. % of a dissolved chloride salt selected from magnesium chloride, calcium chloride, and zinc chloride, calculated on the weight of the liquid, to reaction conditions, thereby obtaining a succinic acid ester, and recovering the succinic acid ester and an aqueous solution comprising the dissolved chloride salt. It has been found that the process according to the invention shows a high yield and has a high reaction rate. Additionally, it has been found that the process makes it possible to carry out the separation of the succinic acid ester from the aqueous reaction medium in high yield.