Fluxes of formic (HCOOH) and acetic (CH3COOH) acids between soils and the atmosphere were measured in a scrub-grass savanna and a semideciduous forest of Venezuela. High emissions of both acids were observed from savanna soils during daytime, with a daily contribution to the atmospheric boundary layer of about 0.15 ppb HCOOH and 0.07 ppb CH3COOH. Soil watering, simulating rainfall, produces a significant increase in CH3COOH emissions. Forest soils consumed these acids, with deposition velocities of 0.21 and 0.16 cm s-1. Savanna soils appear to be significant source of HCOOH and Ch3COOH to the tropical savanna atmosphere. ¿American Geophysical Union 1991