A new method for performing comprehensive GC x GC in the stop-flow mode is presented. A device was used to pneumatically stop the flow in the first dimension ((1)D) (by applying pressure pulses at the junction between the two columns), while flow was maintained in the second dimension ((2)D). This allowed for better preservation of resolution in the (1)D of the GC x GC chromatograms, and the extension of the (2)D's separation space, reducing or eliminating the extent of wraparound. When increased flow rates in the (2)D were used, sensitivity enhancements were also observed.