Recebido em 23/11/07; aceito em 30/7/08; publicado na web em 18/12/08 COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY (GC × GC). This paper presents the fundamental principles, instrumentation and selected applications of comprehensive two-dimensional gas chromatography (GC × GC). In this technique, introduced in 1991, two capillary columns are coupled and proper modulating interfaces continuously collect the eluate from the first column, transferring it to the second column. The result is a geometric increment in the chromatographic resolution, ensuring separation of extremely complex mixtures in time periods shorter or comparable to those of analysis using conventional gas chromatography and with better detectabilities and sensitivities.