Using Sun-tracking photometers onboard balloon, the Pinatubo volcanic aerosol layer has been studied over Hyderabad (17.5¿N) in October 1991, about 4 months after the eruption. From the aerosol extinction coefficients the mode radius and from the angular distribution of the scattered radiation intensity measurements the asymmetry factor g are determined. Mode radii are found to be in the range of 0.22¿0.05 &mgr;m within the aerosol layer while g values are found to be 0.83¿0.04, indicating the presence of larger particles. The mass determination reveals that the mass of the Pinatubo layer is about 0.053 gm-2 which is 3.75 times higher than the earlier reported value for El Chichon layer, about 4 months after the eruptions. ¿ American Geophysical Union 1994