Technical and pure grades of the combustibles heptane and dodecane were used in a series of small-scale fire tests conducted in a 1 m(3) compartment that was mechanically ventilated at 5 and 8 air changes per hour (ACH). Combustible mass loss rates, soot mass concentrations, soot size distributions, several gas species concentrations, and compartment temperatures were measured during the fire. Results for the two pure-grade hydrocarbons were compared with results obtained for their respective technical grades. Technical-grade dodecane produced the highest soot emissions; pure n-heptane produced the lowest. Soot size distributions of all four combustibles attained a steady profile whose modal diameter was about 200 nm. Underventilated fires showed higher carbon monoxide yields than soot yields. Both compartment ventilation rates produced similar results, although the fire self-extinguished earlier for 5 ACH. (C) 2016 Elsevier Ltd. All rights reserved.