W-doped ZnO nanocomposite (W-ZnO) is easily prepared and characterized using a variety of techniques including XRD, TEM, BET, ICP-OES and SEM. This reagent can be used as an efficient and heterogeneous catalyst for the preparation of biscoumarins in water under mild conditions. Easy preparation of the catalyst, mild reaction conditions, easy work-up procedure, excellent yields and short reaction times are some of the advantages of this work. In addition, in this article and for the first time, the preparation of biscoumarins from the protected derivatives of aldehydes including oximes, hydrazones and 1,1-diacetates is reported.