Hypochlorous acid is a cleansing agent known as bleach in daily life. Apart from the household chemicals feature, HOCl plays an active role in the defence system of living cells. It is an important reactive oxygen species that exhibits anti-microbial properties against invaders. However, the increase in the amount of cells in the cell due to oxidative stress causes serious damage to the structure and function of the organism and can cause fatal diseases. Determination of reactive oxygen species in the cell is of great importance. Although different detection methods are used for this purpose, fluorescent sensors are preferred for their precision, easy preparation, high resolution, and quick response. In this study, a "turn on" probe has been designed to detect HOCl based on these reasons. Anthracene dye has been found to be non-fluorescent due to PET when derivatized with phosphorus. In the presence of HOCl, it was determined that the phosphorus was oxidized, inhibiting PET and causing fluorescent radiation. The aim of this thesis is to examine the spectroscopic analysis of the probe which is developed as sensitive to HOCl in various ways and to display the presence of HOCl in the living cell.