It is hypothesized that metal oxides may exist in some drinking water distribution systems capable of oxidizing iodide and possibly bromide producing species that can react with natural organic to form halo-organic compounds of possible health concerns. This hypothesis is based on recently obtained experimental evidence indicating that lead oxide (PbO2), an oxide that can accumulate in distribution systems and on household plumbing fixtures, has the capacity to oxidize iodide. The primary objectives of this research are to demonstrate proof-of-concept of this novel reaction pathway, and to investigate factors that influence the extent and rates of the reactions. Studies will initially focus on the lead oxide-iodide-NOM system and measurement of selected iodo-organic compounds. Additional studies will be conducted using several other oxides. If iodide is found reactive, then oxidation of bromide will also be evaluated to determine if formation of bromo-organic compounds is also possible at environmentally relevant conditions.