A specific surface antigen, OmpD has been reported first time as a surface biomarker in the development of selective and sensitive immunosensor for detecting Salmonella typhimurium species. The OmpD surface antigen extraction was done from Salmonella typhimurium serovars, under the optimized growth conditions for its expression. Anti-OmpD antibodies were generated and used as detector probe in immunoassay format on graphene-graphene oxide (G-GO) modified screen printed carbon electrodes. The water samples were spiked with standard Salmonella typhimurium cells, and detection was done by measuring the change in impedimetric response of developed immunosensor to know the concentration of serovar Salmonella typhimurium. The developed immunosensor was able to specifically detect S. typhimurium in spiked water and juice samples with a sensitivity upto 101CFUmL−1, with high selectivity and very low cross-reactivity with other strains. This is the first report on the detection of Salmonella typhimurum species using a specific biomarker, OmpD. The developed technique could be very useful for the detection of nontyphoidal Salmonellosis and is also important from an epidemiological point of view. •A specific surface antigen, OmpD is reported first time for detecting Salmonella typhimurium.•The OmpD extraction was done under the optimized growth conditions.•Anti-OmpD antibodies were generated, and were used as detector probe•rG-GO nanocomposites modified SPE were used for the developed immunosensor.•The immunosensor specifically detect S. typhimurium in water and juices samples upto 10CFUmL−1.