Measurements and analyses were performed on high-temperature and high-pressure vapor-liquid distribution in the hot separator and the reactor of a 1-t/d coal liquefaction process supporting unit (PSU), which simulated the NEDOL process. The vapor-to-liquid molar ratio, measured for the individual fractions of coal-derived oil in the hot separator, was found to decrease from 1.0 to 0.01 with an increase in the average boiling-point temperature from 373 to 798 K. The measured ratios generally coincided well with those calculated using the Soave-Redlich-Kwong (SRK) equation, with a slight discrepancy for fractions having boiling point temperatures lower than ca. 470 K. The slurry, when directly collected from the reactor, was significantly concentrated due to vaporization of oi 1. Based on the degree of concentration of the slurry, the fractional weight of vaporized oil was estimated to 0.7 or greater, depending on the reactor temperature and the feed ratio of gas to slurry. The observed fractional weights were also well approximated based on the SRK equation. These findings were utilized in operation and optimization of a 150-t/d pilot plant for the NEDOL process.