Abstract Biomass has enormous potential for use in the chemical industry. It is a source of a large number of chemical components and manufactured products. Lignocellulosic biomass can be a source of high-value products produced on an industrial scale in a profitable way. The aim of this study was to determine the chemical composition of seven varieties and clones of willow grown in the moderate climate of Europe and to choose cultivars which can provide a sufficient quantity of feedstock to operate an integrated multiproduct biorefinery. The biomass of the willow cultivars under study had good thermophysical compositions and they contained only small amounts of undesirable components (ash, sulphur, chlorine). The average higher heating value and lower heating value of willow biomass was 19.50 MJ kg−1 d.m. and 8.38 MJ kg−1, respectively. The content and yield of cellulose and hemicelluloses in biomass of the UWM 006 and UWM 043 clones of Salix viminalis L. makes them highly useful for an integrated multi-product biorefinery, based on lignocellulosic raw material.