Resumo. The litter production and decomposition of three sandy coastal plain forest formations periodically floodable in the Island of Marambaia, Mangaratiba, RJ, were studied from October 2005 to September 2006. For the litter deposition evaluation, 10 litter traps were installed and in each forest formation to quantify the litter decomposition 15 litter bags were allocated in each area. The annual litter production was 11.3, 10.8 and 11.1 Mg ha-1year-1, to F1, F2 and F3, respectively, the highest deposition was verified in the rainy season. To nutrients devolution, the highest value was observed to N, 130.8 kg ha-1 year-1 in F3. The fraction leaves were of higher contribution in relation to the others in all areas. The litter decomposition, evaluated by constant of decomposition (k) and half time life was 0.0032 g g-1and 217 days (F2), 0.0031 g g-1and 227 days (F3) and 0.0028 g g-1 and 247 days (F1).