Tropolones were efficiently extracted using a supercritical carbon dio
xide extraction procedure from the wood of western red cedar (Thuja pl
icata D. Don). The yields and composition of the extractives obtained
by hot water distillation were compared with those of the extractives
by supercritical carbon dioxide obtained from the same source. The ext
ractive yield with supercritical carbon dioxide was 7.8 fold higher th
an yield of extractives obtained by hot water distillation. The tropol
ones from the extractives obtained by supercritical carbon dioxide was
about 8 times higher than that of the extractives obtained by hot wat
er distillation. The most efficient condition for extracting tropolone
s from the wood of western red cedar was under 300 kgf/cm2 at 40-degre
es-C for 180 min. Thujic acid, nezukone and beta-thujaplicin were pres
ented in large amounts in the extractives obtained by supercritical ca
rbon dioxide. Nearly ninety percent of the extractives obtained by the
present method were composed of the above tropolones.