Our planet is covered with water in which a large number of ions play various roles. Ion selective sensors are important tools for the detection of ionic species in both qualitative and quantitative ways. Ionophore based ion selective optical sensors (optodes) are very specific and versatile owing to the use of highly selective ionophores. This type of ion selective sensors is often composed of an ionophore, an ion exchanger and a chromoionophore. In this thesis work, ion selective sensors based on polymeric films, microspheres and nanospheres are presented. In addition, new approaches for photoelectric conversion are also described.