Effective removal of organic pollutants from wastewater becomes notable research because of its ecological and environmental importance. In the present study Andrographis echioides leaf extract was used for the synthesis of calcium hydroxide nanoparticles (Ca(OH)2-NPs) from calcium oxide as the calcium source. The secondary metabolites present in the plant source act as a capping agent for the formation Ca(OH)2-NPs. Further NPs were applied for photocatalytic degradation. The intention of the approach is to be low-cost preparation and easy degradation (degradation of dye without any effect) to the environment. The synthesized Ca(OH)2-NPs was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultra violet diffuse reflectance spectroscopy, energy dispersive X-ray spectroscopy, zeta potential and high-resolution transmission electron microscopy. The photocatalytic degradation of methylene blue (dye pollutant) studied under three different light sources such as UV, visible and sun light using Ca(OH)2-NPs. Degradation efficiency of Methylene blue dye examined under UV–Vis spectroscopy. Degradation percentage of Ca(OH)2-NPs under UV, visible and sunlight are (98.96, 97.52 and 96.38%) respectively. The overall study suggests that Ca(OH)2-NPs exhibit excellent photocatalytic property against UV, visible and sunlight. © 2017, Springer Science+Business Media, LLC.