In present study a chromium (III) selective sensor based on dibenzo-18-crown-6 as a macrocyclic ionophore was fabricated. The best operation obtained in the membrane including: 5.0 mg dibenzo-18-crown-6 (DB-18C6), 4.0 mg sodium tetraphenylborate (NaTPB), 61.0 mg dioctyl sabacate (DOS) and 30.0 mg polyvinyl chloride (PVC). This electrode has a good selectivity respect to Cr3+ cation, with a nernstian slope of 19.6±0.1 mV/decade in a linear concentration range of 1.0×10-5 M-1.0×10-1 M. The detection limit of the electrode is 8.8×10-6 M. The porposed sensor has a fast response time of 5 s and good reproducibility. It can be used for a period of 63 days without any significant changes in its potential. The effects of the pH and possible interfering ions were investigated. This electrode was employed as an indicator electrode in potentiometric titrations of chromium cation with EDTA solutions and a sharp break in titration curves around the equivalent point was observed. This sensor was successfully used for the determination of chromium (III) in real samples. تفاصيل المقالة