Sediment from a representative and ecologically important backwater wetland under the influence of River Tisza (Hungary) was chemically characterized for sediment pollutants. Phosphine production potential, methyl mercury, mercury, and other heavy metals were determined along with other sediment chemical and physical properties. The wetland site, which is relatively isolated, represents an important bird reserve and nature conservation area. Methyl mercury and total mercury content was also low reflecting little mercury pollution in the sediment. Results of heavy metal analysis showed that only copper was elevated with concentration slightly above the reported levels considered excessive in soils and sediments. Other sediment properties were in normal range except boron content, which was high. Results show sediment were relatively unpolluted but should be routinely monitored to insure that this ecologically important area remains environmentally safe for future generation.