The QM7b data set is a collection of information on over 7211 small organic molecules containing up to seven different elements: C, Cl, H, N, O, and S. It serves as an extension of the QM7 data set specifically designed for multitask learning applications in chemistry. Each molecule is described by 14 properties, including atomization energy, static polarizability, frontier orbital eigenvalues (HOMO and LUMO) and excitation energies.