The combustion chemistry of di-n-butyl ether (DBE, C8H18O), conceivable as a potential biofuel candidate, was studied here for the first time under flame conditions with examining a detailed species dataset. Two flames, i.e., a fuel-rich (phi = 1.5) and a fuel-lean (phi = 0.8) one, were analyzed at the same pressure (4 kPa), argon dilution (50%), and cold-gas velocity (60 cm s(-1)) by molecular-beam mass spectrometry (MBMS) using electron ionization (El). About 50 species including reactants, diluent, combustion-related intermediates, and products, were detected with a special interest in fuel-specific intermediates, harmful species as well as important soot precursors. n-Butanal was detected in high concentration and identified as an important fuel-specific intermediate in the DBE flames, while cyclic soot precursors (e.g., 1,3-cyclopentadiene, benzene, toluene) were detected with low mole fractions (similar to 10 ppm). The present experimental data were compared to simulations by the kinetic model of Cai et al. [Combust. Flame 161 (2014)] and the very recent model of Thion et al. [Combust. Flame 185 (2017)], with the dual purpose to support the data interpretation and to examine the performance of these models also in comparison to each other. Note that species in the range of C-5 to C-7 (known as important soot precursors) that are not yet addressed in either of the models have been well detected and are presented in the present work. For further insight into the combustion chemistry of DBE, its fuel-rich flame was also compared to those of successively smaller ethers, namely dimethyl ether (DME) and diethyl ether (DEE). This comparison showed a strong effect of the aliphatic side chains of ethers on the formation of intermediate species. Not unexpectedly, increasing the length of side chains enhances the formation tendency of larger unsaturated hydrocarbons. However, the contribution of highly toxic carbonyl compounds, namely formaldehyde and acetaldehyde, was found to be much lower upon the use of DBE as a fuel than for DME and DEE, respectively. Similarly, DBE was also compared to its half-structurally similar fuels, i.e., n-butane and n-butanol. This comparison generally indicates that the distribution of hydrocarbon species (except for C4H8) in DBE flames is quite similar to those in n-butane and n-butanol flames, whereas the formation of oxygenated species is very different for the three fuels. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.