In the present study, a cost-effective, green and simple synthesis method for preparation of stable silver chloride nanoparticles (AgCl-NPs) has been applied. The method is done by forming AgCl-NPs from Ag+ ions using aqueous extract of brown algae (Sargassum Boveanum) obtained from the Persian Gulf. This extract has been served as capping agent at the same time. Creation of AgCl-NPs has been confirmed by UV–visible spectroscopy, powder X-ray diffraction, energy Dispersive X-ray spectroscopy and high resolution transmission electron microscopy, while size analysis has been gathered from high resolution transmission electron microscopy. After optimization of some experimental condition particularly pH, a simple and facile system has been developed for the naked-eye detection of Bisphenol-A. It seems that intermolecular interaction such as electrostatic and van der Waal interaction play important roles in complexation of Bisphenol-A with AgCl-NPs, which can lead to aggregation of the as-prepared AgCl-NPs and result in color change from specific yellow to dark purple where new aggregation band induced at 542 nm appears. The absorbance at 542 nm has been found to be linearly dependent on the Bisphenol-A concentration in the range of 1×10-6 -1×10-4 M, with limit of detection 45 nM. The same procedure have been applied for detecting hydrogen peroxide too. However the optimum pH was the neutral (pH=7). At the optimum pH, the selective signal at 417 nm can be related to hydrogen peroxide concentration. Interestingly, the color of solution in this condition was change from yellow to colorless. The linear region in the optimum condition has been obtained in the range of 1×10-6 -120×10-6 M, with limit of detection 32 nM . In order to check the selectivity of our colorimetric sensor, in both cases (Bisphenol-A and hydrogen peroxide) several common interferences have been checked. In conclusion, the reported results here can open up an innovative application of the green synthes