Perchlorate () is an emerging environmental contaminant reported from many parts of the world. As per World Health Organization guidelines, the provisional maximum tolerable daily uptake of in drinking water is 0.1 μg kg−1 body weight per day. Meanwhile, has been traced in different matrices including human consumption products in many countries (Hogue, 2003; Sanchez et al., 2005; Kannan et al., 2009). Bioremediation has been identified as an effective method for detoxifying (Attaway & Smith, 1993; Bardiya & Bae, 2011). Dissimilatory perchlorate-reducing bacteria under anoxic conditions utilize as an electron sink, sequentially reducing it to Cl−. Bacterial reduction involves two enzymes, perchlorate reductase and chlorite dismutase, coded by pcrABCD and cld genes, respectively (Bender et al., 2004, 2005). Studies on the biochemical mechanism and genetic regulation of reduction and diversity of perchlorate-reducing bacteria including their kinetics of growth and reduction have been well reported (Logan, 1998; Coates & Achenbach, 2004; Yu et al., 2006). Perchlorate-laden waste/discharges like ion exchange spent resin and regenerate solution can have salinity up to 15% (Chung et al., 2007) and pH either alkaline or acidic (Batista et al., 2002). Moreover, inhibition of reduction by competitive and co-occurring electron acceptors like nitrate () is encountered in a number of studies (Chaudhuri et al., 2002). Therefore, high salt- and exteme pH-tolerant perchlorate-reducing bacteria that reduce and simultaneously are significant. In spite of this, only few studies have reported reduction under high salt and extreme pH conditions. The maximum tolerance to salinity and pH by perchlorate-reducing bacteria reported so far was 7.5% and 6–9, respectively, by a Citrobacter sp. (Okeke et al., 2002). Perchlorate-reducing consortia tolerating 11% salinity (Logan et al., 2001) and pH 5–9 (Wang et al., 2008) were also reported previously. In this study, we report a Serratia marcescens strain, tolerating high salt and extreme pH and reducing and NO3 simultaneously.