Decomposition dynamics of two types of litter (butterbur Petasites spp. and beech Fagus sylvatica L.) was analysed in the period from December 2006. to November 2007. on two tufa barriers of Plitvice Lakes. Experiments using leaf bags were carried out in three time series on two rheotopes (fast and slow current velocity) on each barrier. Chemical changes of the litter and the surrounding water were also analysed, as well as tufa deposition on litter surface and weight changes of tufa cubes embedded in the bag with the decaying litter. Litter decomposition rates were dependent on current velocity, water temperature and tufa deposition rate, except in the initial stage. The effect of tufa deposition on the litter decomposition rate proved to be different for the two types of litter: after prolonged exposure to calcification and under the influence of slow currents in combination with high tufa deposition rate, it even acted inhibitory on the decomposition of beech, while the same process accelerated decomposition of fast-decomposing butterbur. Leaf litter decomposition mainly accelerates tufa deposition with the exception of the initial stage of calcite deposition (up to 30 days) or at lower intensity of calcification, when dissolution of tufa was noticed.