[en] Highlights: • Critically reviewed constants for isosaccharinate reactions with several elements. • Summarized equilibrium constants for ISA reactions with actinides, Ca, and Fe(III). • Outlined studies to acquire further needed reliable thermodynamic data. - Abstract: Isosaccharinic acid is a cellulose degradation product that can form in low-level nuclear waste repositories and is known to form strong complexes with many elements, including actinides, disposed of in these repositories. We 1) reviewed the available data for deprotonation and lactonisation constants of isosaccharinic acid, and the isosaccharinate binding constants for Ca, Fe(III), Th, U(IV), U(VI), Np(IV), Pu(IV), and Am(III), 2) summarized complexation constant values for predicting actinide behavior in geologic repositories in the presence of isosaccharinate, and 3) outlined additional studies to acquire reliable thermodynamic data where the available data are inadequate.