Volatile organic compounds (VOCs) are hazardous air toxics, as well as important in the formation of secondary air pollutants including ozone. Measurements of VOCs are in particular important in Houston, TX, one of the largest and highly industrialized metropolitan regions in the US: the high ozone levels in Houston are attributed to anthropogenic NOx and VOC sources producing ozone under intensive solar radiation and stagnant meteorological conditions. Besides typical urban emission sources such as motor vehicle, the impact of the large petrochemical industrial sector, as well as biogenic VOCs have to be taken into account, when evaluating air quality in Houston area. Here we will report results of a wide range of VOCs obtained within the frame of the Study of Houston Atmospheric Radical Precursors (SHARP) campaign in late spring 2009. Measurements were carried out using online GC-FID and PTR-MS instrumentation, located on the rooftop of the University of Houston Moody Tower building, which is an ideal location to look into different source fingerprints. For the VOC sources identification and evaluation of their respective contributions the EPA Principle Matrix Factorization (PMF) 3 receptor model will be used. Additional data collected at the site, located near Houston Ship Channel and highly affected by surrounding industrial facilities, motor vehicles and heavy-duty diesel truck emissions will be included for comparative purposes.