A thiol amine surfactant, poly-3-(dodecylthio)-N-hexadecylacrylamide (iphI) was prepared and characterized using spectral methods of analyses. The proposed potentiometric method was based on the fabrication of iphI-modified carbon paste (iphI-MCPE; electrode IV) sensor. Fast, highly sensitive and wide dynamic range potentiometric sensor was constructed using the prepared ionophore to quantify Cr(III) ions in spiked water sample under optimum conditions. The electrode (IV) exhibited an excellent Nernstian response to Cr(III) ion ranging from 4.8 × 10-7 to 1.0 × 10-2 mol L-1 with a detection limit of 4.8 × 10-7 mol L-1 and a slope of 19.59±0.45 mV decade-1 over a wide pH range (2.0-8.0) with a fast response time (7 s) at 25 oC. The proposed sensor showed fairly good discriminating ability towards Cr(III) ion in comparison with many hard and soft metal ions. The developed electrode has been successfully applied for the Cr(III) ions potentiometric determination in different water samples. The results obtained compared well with those obtained using atomic absorption spectrometry.