Using a novel experimental technique, based on proton transfer reaction mass spectrometry, from measurements of emissions from laboratory scale biomass burning experiments, we have estimated the source strengths of several potential HOx producing gases: formaldehyde, acetaldehyde, methanol and acetone. The derived global average emissions are 5--13; 3.8--10; 1.5--4; 2.3--6.1 Tg y-1, respectively. The resulting global average HOx production from photochemical decay of these gases is 3¿109 molecules cm-2 s-1. Although relatively small in a global context, these emissions are significant for the photochemistry in fresh fire plumes. From our measurements are also estimated global source strengths from biomass burning for CH3CN and HCN of 0.4--1.0; 0.2--0.6 Tg y-1 respectively. The biomass burning emissions of CH3CN may well dominate the global source of this compound, which thus might well be a unique tracer for biomass burning. Some discrepancies between experimental studies must, however, be resolved. ¿ 1999 American Geophysical Union