In gas-liquid agitated vessels the flooding stage is generally used as a design criterion. The flooding stage is a characteristic dispersion stage which must be avoided in order to achieve efficient dispersion characteristics, while the identification of this flooding-loading transition helps also determining the complete dispersion stage. Several methods have been applied for the determination of the flooding-loading transition point. In this work, the light transmission method is used as a new technique for identification of this point in an air-water dispersion system, agitated by a single six-blade disc turbine. Using a relatively simple instrumentation, satisfactory results have been obtained. The method suggested is reliable, does not interfere with the fluid dynamics of the system, and is also applicable to nontransparent industrial reactors.