Effective separation of individual components continues to pose the greatest challenge in the characterization of complex hydrocarbon mixtures. Recent research has tackled this problem using several different multidimensional separation techniques such as coupling gas chromatography to a vacuum ultraviolet (VUV) spectrometer. Total absorption signals from the VUV spectrometer allow for general-purpose detection that is well suited for quantitative analysis. Full-range VUV spectra also can be collected that provide additional chemical information with absorption bands correlating to specific structural groups. When hyphenated with an advanced gas chromatography separation technique such as GC X GC, the full-range VUV spectrum can be used as a third dimension of separation. In this study, the three-dimensional technique, namely, comprehensive two-dimensional gas chromatography hyphenated with a vacuum ultraviolet spectrometer (GC X GC X VUV), is demonstrated using a diesel sample. The separation of various compounds that chromatographically coelute and the resolution of isomers that cannot be separated by mass spectrometry or any other analytical technique illustrate the power of this new analytical capability.