Anthropogenic 137Cs activity concentration, in surface sea water along the western and eastern coast of India has been estimated using the in-situ pre-concentration approach. Activity levels of 137Cs ranges from 0.09–1.30 Bqm−3 with an overall mean of 0.69 ± 0.29 Bqm−3. Latitudinal variation and higher depletion in activity concentration of 137Cs at few locations were observed. Temporal change of 137Cs in sea water along Indian coast unveils a lower effective half-life of 13.8 ± 0.7 y in comparison to Asia Pacific regional sea water. The results prevailed that the spatial distribution confers no fresh input of 137Cs in Indian coastal region.