The use of chlordecone as the active ingredient in pesticide formulations has resulted in extensive pollution of large land areas in the French West Indies. These areas were treated with pesticides to control the banana black weevil. Although the use of these pesticides is currently banned, chlordecone strongly adsorbs to soil and is highly recalcitrant due to its complex bis-homocubane structure. In order to investigate the biodegradability of chlordecone, microcosms were constructed anaerobically from chlordecone impacted Guadeloupe soil and sludge. The microcosms were incubated and repeatedly amended with chlordecone and electron donor (ethanol and acetone) over a period of 7 years. DNA was extracted from some of the microcosms, and the microbial community was analyzed using 16S amplicon sequencing (Illumina MiSeq). Degradation products of chlordecone were detected in all the biologically active microcosms. Observed products include monohydro- and dihydrochlordecone derivatives (C10H10-nO2Hn+1 n= 1,2), as well as C10- and C9- polychloroindene compounds (C9Cl5-nH3+n n=0,1) and carboxylic indene derivatives (C10Cl4-nO2H4+n, n=0-4) assumed to be “open cage” structures with significant dechlorination also characterized in other studies (1,2,3) but which are not present in sterile controls. Chlordecone concentrations decreased in active microcosms. Results from microbial community analysis show enrichment of several organisms possibly involved in chlordecone biodegradation. In two microcosms with no methanogenesis we see high relative abundance of Desulfovibrio and Sporomusa, while in two of the microcosms with methane production, we see enrichment of two highly similar Anaerolinaceae species (Pelolinea and Leptolinea), Bathyarchaeota, and two methanogens (Methanoregula and Methanosaeta). The metabolites identified in this study are also detected in the field, showing that a bioremediation process could be envisioned. Stimulatation pf dechlorination in farmer’s fields can be considered by inducing reducing conditions with substrate addition and restricting oxygen entry.