Gate-to-gate process energy for 86 chemical manufacturing processes is presented. The estimation of the process energy follows design-based methodology. Results show that the gate-to-gate process energy for half of organic chemicals ranges from 0 to 4 MJ per kg, and for half of inorganic chemicals ranges from -1 to 3 MJ per kg. The main energy source in both organic and inorganic processes is steam energy followed by potential recovered energy. In organic chemicals, the fractions of heating oil and electricity use are relatively low, but these fractions are higher in the inorganic chemicals than in the organic chemicals. Furthermore, about 50% of the energy consumed in chemical processes is used for purifying the product, byproduct or recycled stream, which indicates that there are large opportunities for improving the process energy in chemical processes. The information presented in this study is very important for those in the life cycle assessment community in order for them to identify inaccurate information or information not based on actual process design. However, the range for the entire range of chemicals is very substantial and thus reflects the need of the life cycle inventory to separately evaluate the chemistry and degree of purity for chemical products. (C) 2003 Society of Chemical Industry.