Volatile organic compounds (VOCs) emitted from smoldering mosquito coils containing various atomic hydrogen/carbon (H/C) ratios in different relative humidity were examined. The concentrations of individual VOCs were determined using a preconcentrator-gas chromatography/mass spectrometer (GC/MS) and a flame ion detector (FID). Up to 72 VOCs were found. It is noteworthy that benzene and 1,3-butadiene, human carcinogenic substances, were emitted by all tested mosquito coils during burning. The five types of mosquito coils studied had atomic H/C ratios ranging from 1.23 to 1.57, yielding total VOC emission rates and factors of 7,295.72–14,308.17 µg hr–1 and 3,192.78–6,835.03 µg g–1, respectively. VOC emissions were significantly influenced by the carbon, hydrogen and oxygen contents of coils. According to the analyses of VOC emissions, mosquito coils containing the lowest H/C ratio, a low oxygen content, with suitable additives such as CaCO3 are recommended for minimizing total VOC emission.