We report a microfabricated gas chromatography (GC) column that uses a thin layer of high‐quality single‐walled carbon nanotubes
(SWNTs) as a stationary phase. This 1.0‐m‐long, 160‐μm‐wide, 250‐μm‐deep column has the highest separation efficiency reported to date for microfabricated columns having an SWNT stationary phase. Separation efficiency was evaluated with a Golay plot, in which the minimum of the height equivalent to a theoretical plate was 0.062 cm. The microfabricated column was able to separate n‐alkanes having high boiling points under temperature‐programmed conditions. Use of SWNTs as a stationary phase will be potentially useful for high‐performance micro‐GC.