The conversion of organic wastes by anaerobic fermentation (the so-called carboxylate platform) is one of the promising emerging biorefineries that allows valorising organic carbon to volatile fatty acids (VFA), which can be further processed as chemicals, biopolymers and biofuels. A major obstacle to the widespread of the carboxylate platform is the poor selectivity, leading to a mix of mainly acetic, propionic, butyric and valeric acid. There are some guidelines that lead to a moderately selective acetic and butyric acid mixture, but the selective production of propionic and valeric acids, odd-chain VFA, remains elusive. Beyond the applications of propionic and valeric acids as chemicals, it is particularly relevant their use as substrate in the production of polyhydroxyalkanoates (PHA), bio-sourced and biodegradable plastic materials. The project ODDITY tackles the challenge of the selective valorisation of organic wastes into odd-chain VFA with a multidisciplinary approach that integrates technical, microbiological and environmental contributions in a mathematical modelling framework.