Cocoa fermentation was monitored at the IDIAF (Instituto Dominicano de Investigaciones Agropecuarias y Forestales) "Mata Larga" experimental station, in San Francisco de Macoris, Dominican Republic. The maximum average fermentation temperature reached 51°C after 48 h and the pH reached 4.5 after 144 h of fermentation. A significant decrease in glucose, fructose and citric acid was seen in the pulp over the first 48 h. There was a delay of 24 h between maximum microbial growth and maximum concentrations of the respective metabolites, which occurred after 48 h for ethanol and after 72 h for acetic acid. A maximum concentration in lactic acid was found after around 120 h of fermentation. The aerobic mesophilic flora increased from 6.1 × 106 to a maximum of 4.2 × 107 CFU g-1 of dry matter after 48 h of fermentation. Yeasts displayed maximum development after 24 h (6.1 × 107 CFU g-1 of dry matter), whilst for lactic and acetic acid bacteria it occurred after 48 h (7.3 × 107 and 1.5 × 108 CFU g-1 of dry matter respectively). The yeasts isolated belonged to the genera Hanseniaspora and Candida, the lactic acid bacteria to the genus Lactobacillus, and the acetic acid bacteria to the genus Acetobacter. The differences compared to other fermentation trials concerned the micropopulation from a qualitative point of view. © 2006 Elsevier B.V. All rights reserved.