The construction and performance characteristics of new sensitive and selective in situ modifed screen printed(ISPE)and carbon paste(ICPE)electrodes for determination of naphazoline hydrochloride(NPZ-HCl)have been developed.The electrodes under investigation show potentiometric response for NPZ-HCl in the concentration range from 7.0 10–7to 1.0 10–2M at 25 1C and the electrode response is independent of pH in the range of 3.1–7.9.These sensors have slope values of59.770.6 and 59.270.2 mV decade 1with detection limit values of 5.6 10–7and 5.9 10–7M NPZHCl using ISPE and ICPE,respectively.These electrodes show fast response time of 4–7 s and 5–8 s and exhibits lifetimes of 28 and 30 days for ISPE and ICPE,respectively.Selectivity for NPZ-HCl with respect to a number of interfering materials was also investigated.It was found that there is no interference from the investigated inorganic cations,anions,sugars and other pharmaceutical excipients.The proposed sensors were applied for the determination of NPZ-HCl in pharmaceutical formulation using the direct potentiometric method.It showed a mean average recovery of 100.2%and 102.6%for ISPE and ICPE,respectively.The obtained results using the proposed sensors were in good agreement with those obtained using the offcial method.The proposed sensors show signifcantly high selectivity,response time,accuracy,precision,limit of detection(LOD)and limit of quantifcation(LOQ)compared with other proposed methods. The construction and performance characteristics of new sensitive and selective in situ modifed screen printed (ISPE) and carbon paste (ICPE) electrodes for determination of naphazoline hydrochloride (NPZ-HCl) have been developed. These electrodes under investigation show potentiometric response for NPZ-HCl in the concentration range from 7.0 10-7to 1.0 10-2M at 25 1C and the electrode response is independent of pH in the range of 3.1-7.9.These sensors have slope values ​​of 59.770.6 and 59.270.2 mV decade 1 with detection limit values of 5.6 10-7 and 5.9 10-7 M NPZHCl using ISPE and ICPE, respectively. These selections show fast response time of 4-7 s and 5-8 s and exhibits lifetimes of 28 and 30 days for ISPE and ICPE, respectively. Selectivity for NPZ-HCl with respect to a number of interfering materials was also investigated. It was found that there is no interference from the investigated inorganic cations, anions, sugars and other pharmaceutical excipients. The proposed sensors were appli ed for the determination of NPZ-HCl in pharmaceutical formulation using the direct potentiometric method. It showed a mean average recovery of 100.2% and 102.6% for ISPE and ICPE, respectively. The resulting results using the proposed sensors were in good agreement with those obtained using the offcial method. The proposed sensors show signifcantly high selectivity, response time, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ) compared with other proposed methods.