Low-cost sensors measuring volatile organic compounds (VOCs) can be of interest for reducing energy use for ventilation in buildings and maintaining good indoor air quality. However, the accuracy of many of these sensors remains unclear. This study aims to evaluate four different VOC sensors available on the market by exposing them to known concentrations of the VOC-gases in ISO 16 000-29: m-xylene and n-octane (mixed), alpha-pinene, and methyl-isobutyl-ketone (MIBK). The VOC sensors tested were metal oxide semiconducting sensors, and two copies of each sensor were included. Results show that all four sensors did not respond to every test gas. Moreover, two copies of the same sensor did not give the same output. Further, the output from the different sensors varied considerably. For the reference 110 ppb alpha-pinene, the sensors output varied from 810 to 1650 ppb. Reference concentration for MIBK: 180 ppb with sensor output: 230-1040 ppb, and reference concentration for mixed gas: 100 ppb with sensor output: 220-730 ppb. Although the results seem discouraging, several of the sensors did respond to changes in concentration of the test gases and thus might be used for ventilation control purposes. Nevertheless, there is a need to evaluate and verify VOC sensors before using them for control of IAQ