An optical sensor (optode) is described based on a plasticized poly(vinyl chloride) (PVC) bulk membrane incorporating an uranyl ion-selective ionophore, an H+-selective chromoionophore that changes its absorption spectrum upon protonation, and a lipophilic anionic site. The measuring range for uranyl was found to be 10(-7)10(-4) mol/l at pH 3.6. The selectivities over 11 alkali, alkaline earth and heavy metals were investigated. The sensor shows perfect short time repeatability and during 3 days of work no significant loss of chromoionophore or decay of anionic site was observed.