Chemical sensors are devices which can detect or measure analytes by converting chemical information about the concentraction of a component in a sample into an analitically useful signal. Fluorescent sensors measure radiative decay, that is emission of a fluorophore. The main characteristic of those sensors is selective quenching or increasing of the fluorescence intensity when in contact with an analyte (On-Off effect). 4-amino-1,8-naphthalimides and their derivatives are commonly used fluorescent dyes. They became versatile platforms for sensor design due to their advantageous optical properties, such as strong absorption and emission in the visible region, large Stokes shift, high photostability etc. Secondly, they are typical fluorophores with intermolecular charge transfer, which enables sensitivity to changes in the microenviroment. Lastly, but equally important, they have relatively simple structure, for which facile synthesis have been established. Property of 1,8-naphtalimide derivatives is photoinduced electron transfer (PET), which occurs from electron donor to carbonyl groups located on a fluorophore. PET process decreases the rate of the radiative decay. Depending on the structure of the derivative, either increase or quenching of fluorescence can occur. In this paper the mechanism of fluorescent PET sensors containing the derivatives od 1,8-naphthalimides is studied, where different aspects can influence its properties, such as position of the supstituent, distance of electron donor and acceptor, specific interactions and the ligand geometry. The great emphasis is on optical properties in solutions of different metal cations and pH, making the base of sensoric design. In addition, immobilisation methods to different substrates are listed; cotton fabric, polymers, glass, molecular sieves and cellulose nanoparticles, where covalent bonding has great advantages. Due to the promising characteristics shown, 1,8-naphthalimide-based fluorescence sensors could be used in actual water samples of different origins.