This dataset was created as a compilation of experimental data in the literature on the production of medium chain carboxylic acids (MCCAs) by microbial mixed cultures (MMC) fermentation. The intention was to provide a dataset as comprehensive as possible that includes the majority of experimental results available in this research area to the best of our knowledge. The focus lied on MMC-based studies processing complex organic feedstock, yet selected studies were included on synthetic substrates. The relevant literature studies were collected and experimental results categorized according to bioreactor operation, i.e. batch, fed-batch and (semi-)continuous. Operational parameters, such as feedstock type, organic loading rate, temperature, etc., were extracted from information reported in studies and placed alongside product outcome in terms of MCCA production for each experiment. This dataset forms the backbone of the discussion and figure generation of the literature review "Medium chain carboxylic acids from complex organic feedstock by mixed culture fermentation" by V. De Groof, M. Coma, T. Arnot, D. Leak, A. Lanham. Published in MDPI Molecules: Special Issue "Chemicals from Food Supply Chain By-Products and Waste Streams" 2019.