Oxygenated biofuels work as a promising renewable alternative. Despite the fact that biofuels tend to decrease the soot emissions, they may lead to new emission problems such as the formation of aldehydes (notably formaldehyde and acetaldehyde). In this study, experimental work is carried out to analyze the chemical processes involved during combustion of the oxygenated biofuels. Atmospheric premixed laminar flames of a toluene reference fuel (iso-octane, n-heptane, toluene) mixed with two biofuels (ethanol and butanol) stabilized on a McKenna burner were investigated in fuel-rich flame conditions. Mole fractions of several saturated and unsaturated aliphatics, aldehydes, ketones and aromatic species were measured using gas chromatography in order to elucidate the chemical structure of the flames.