Soot concentration (KL factor) and soot temperature were measured in a constant volume combustion chamber for a new biomass-based biofuel or BTL (biomass to liquid) fuel and regular No.2 diesel. A highspeed camera was employed coupled with two bandpass filters to implement a two-color thermometry method and measure the soot concentration and temperature simultaneously. Ambient conditions were set as follows: three temperatures of 800 K, 1000 K, and 1200 K and four 02 concentrations of 10%, 15%, 18% and 21%. The soot ML factor and temperature spatial distributions are presented for 1000 K ambient temperature. More soot is seen in the near-wall regions under the low ambient oxygen conditions while high level soot is observed in the upstream and midstream for the conventional combustion mode. An analysis was then conducted for the quasi-steady state. The results show that BTL combustion generates a lower integrated ML factor and soot temperature compared to diesel fuel under all the experimental conditions. Additionally, low ambient temperature with a moderate 02 concentration benefits BTL more than diesel due to a larger reduction in the integrated la. factor without increasing soot temperature significantly. Finally, the characteristics of the two-color results were further discussed and analyzed. (C) 2015 Elsevier Ltd. All rights reserved.