Narrow-bore, (5–15 μm), long (up to 6 m), efficient and stable open tubular columns with four different polyorganosiloxane coatings, were prepared by the static coating and the precipitation coating methods. The polysiloxanes were substituted with phenyl- (OV-17-vi and PS-264), methyl- (PS-255), and octadecyl- (PMSC 18) groups. They were studied in their regular cross-linked state as well as after swelling with n-heptane. Anthracene derivatives were used as model compounds. Column properties such as retention, selectivity and efficiency were investigated in reversed-phase liquid chromatography. GC was used for complementary studies of 50 μm I.D. columns. The highest retention was obtained on the columns coated with OV-17-vi and on the swelled stationary phases. A considerable resolution improvement was obtained in the columns, after swelling with n-heptane owing to the increase in retention. More than 10 6 theoretical plates were achieved in 70 min at a k′ of 0.46 in a 6 m ×6 μm I.D. column.