Gas-phase low volatility organic compounds (LVOC), produced during an experiment studying the oxidation of isoprene 4-hydroxy-3-hydroperoxide (4,3-ISOPOOH) under low-NO conditions, were observed during the FIXCIT chamber study. Decreases in LVOC concentrations directly correspond to the appearance and growth in secondary organic aerosol (SOA) of consistent elemental composition, indicating that LVOC condense (at OA levels below 1 µg m-3). This represents the first simultaneous measurement of condensing low volatility species from isoprene oxidation in both the gas and particle phases. The experimental conditions and aerosol composition indicate that SOA formation observed in this study is separate from previously described isoprene epoxydiol (IEPOX) uptake. Comparison with a kinetic model suggests that these LVOC arise as first generation products from the reaction of OH with ISOPOOH and associated species in the experiment. Assigning all condensing LVOC signals to 4,3-ISOPOOH oxidation in the chamber study implies a wall-loss corrected non-IEPOX SOA mass yield of ~4% from this species. By contrast to monoterpene oxidation, in which extremely low volatility VOC (ELVOC) constitute the organic aerosol, in the isoprene system LVOC with saturation concentrations from 10(-2) to 10 μg m(-3) are the main constituents. The ability of these LVOC to condense at low OA levels indicates that they may be important for the growth of nanoparticles in environments with low OA concentrations. LVOC signals observed in the chamber were also observed in the atmosphere during the SOAS 2013 campaign in the SE US, and displayed a similar diurnal cycle to production rates calculated using from measured ISOPOOH and OH. This previously uncharacterized aerosol formation pathway from OVOC products derived from isoprene could account for up to 5.0 Tg yr(-1) of SOA production, or 3.3% of the estimated global SOA source. .