Comprehensive two-dimensional gas chromatography (GC × GC) may be considered one of the most revolutionary inventions in the GC field.Comprehensive GC separations are generally carried out on two capillaries connected in series, with different internal diameters and selectivities.The modulation process is usually achieved with a cryogenic modulator located at the head of the secondary column.Although a wide series of impressive GC × GC separations have been reported, demonstrating the enhanced resolving power of this technique, it may be affirmed that its full potential is not always expressed.Many literature-reported 2D chromatograms are characterized by analyte bands containing closely-eluting or overlapping compounds, with a great deal of unexploited and available chromatographic space.One of the reasons behind this negative aspect is related to the traditional long conventional + short micro-bore column GC × GC configuration, which generates much higher than optimum gas linear velocities in the second dimension, causing substiantial losses in efficiency.