The construction and performance characteristics of tetrazepam selective electrodes were developed. Two types of electrodes: plastic membrane I and coated wire II were constructed based on the incorporation of tetrazepam with phosphomolybdic acid. The influence of membrane composition, kind of plasticizer, pH of the test solution, soaking time, and foreign ions on the electrodes were investigated. The electrodes showed a Nernstain response with a mean calibration graph slope of 58.88±0.5 and 59.18±0.1 mV decade-1 at 25ºC for electrode I and II respectively, over tetrazepam concentration range from 5x10-3-1x10-6M and 1x10-2-1x10-6M, and with detection limit 5.0x10-7 M and 4.8 x10-7M for electrode I and II respectively. The constructed electrodes gave average selective precise and usable within the pH range 4-6. Interferences from common cations, alkaloids, sugars, amino acids and drug excipients were reported. The results obtained by the proposed electrodes were also applied successfully to the determination of the drug in pharmaceutical preparations and biological fluids.