Abstarct: The aim of this investigation is designing optical sensors for determination of Cu(ΙΙ) and CN- ions. The first sensor has been designed for determination of copper(ΙΙ). New chromogenic reagent 1-phenyl-1,2-propanedione-2-oxime thiosemi-carbazone (PPDOT) has been synthesized and utilized to prepare a novel sensing membrane (optode) for determination of copper (II) by immobilizing on triacetylcellulose membrane. The sensing mechanism involves the complex formation between Cu(II) and immobilized PPDOT at pH=5.8, which results in the absorbance increasing at 401 nm. The sensor shows sufficient repeatability, reproducibility, operational lifetime of 3 weeks, and a response of less then 10 min. Cu(II) can be determined in the range between 8.0 × 10−6 and 2.0 × 10−4 mol l−1 with a detection limit of 7.55 × 10−6 mol l−1 with a response time of 8 min. The sensor can be regenerated by placing the film onto a 5 thiourea solution for 5 min and then washing with water. Most commonly coexisting ions do not interfere with the Cu(II) assay. This sensor was used for the determination of copper ion in water and alloy samples with satisfactory results. The second sensor has been designed for determination of free cyanide.This sensor is baxsed on immobilization of crystal violet on a triacetylcellulose membrane. Cyanide ion reacts with the immobilized crystal violet at pH=5.4 and causes a decrease in the absorbance of the film at 600 nm. The sensor shows sufficient repeatability, reproducibility, operational lifetime of 5 weeks, and a response of less then 5 min. This sensing phase has a linear range of 50-850 mg¬L-1 for CN- ions with a limit of detection of 5.5 mg¬L-1 with a response time of 4 min. The sensor can be regenerated by placing the film onto a 10-4M crystal violet solution for 30 sec and then washing with water. The sensor was applied to determination of cyanide in river and tap water.