Efficient Helicobacter pylori elimination requires delivery of the antibiotic locally in the stomach. High dose of metronidazole (250 to 750 mg) is difficult to incorporate in floating tablets but can simply be given in liquid dosage form.  By keeping the above observation in mind, we made an attempt to build up a new raft forming oral in situ gelling system of metronidazole with improved residence time using sodium alginate as gelling polymer to eliminate H. pylori.  Methods: oral in situ gelling formulations were prepared using sodium alginate, xanthan gum, calcium carbonate, and sodium bicarbonate. Prepared formulations were evaluated for density, viscosity, floating lag time, floating duration, swelling index and in vitro drug release. Results. All formulations (F1–F12) showed floating within 180 s and had floating duration  of more than 24 h. every formulations showed excellent pourability. It was observed that concentration of sodium alginate and xanthan gum had major influence on floating lag time, cumulative percentage drug release and other evaluation parameters. The batch F11 was optimized since it have good pourability with extended release of 10 hrs. Conclusion: oral in situ gelling system of metronidazole  can be formulated by  use of sodium alginate as a gelling polymer and xanthan gum as release retardant to control  the drug release for more than  10 hrs.