Soil organic carbon (SOC) contents were examined beneath two grassland vegetation communities and cold desert sites in permafrost areas of the central western part of the Qinghai-Tibet Plateau. Mean SOC stocks in the top 150 cm were 7.73 kg m-2 for Stipa roborowskyi communities and 3.72 kg m-2 for Carex moorcroftii communities, but only 1.84 kg m-2 for cold alpine desert. More than 80 per cent of SOC stocks beneath the grasslands were in the top 100 cm. Correlation analyses showed that SOC stocks in the top 150 cm are linked to soil moisture content, and the vertical distribution of SOC is mainly affected by depth and soil moisture content. Moisture content and vegetation communities are therefore important factors associated with SOC content in this cold, arid area, while active-layer thickness, vegetation cover and topographical factors play non-significant roles in SOC distribution. Copyright © 2012 John Wiley & Sons, Ltd.