Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment to understand aspects of GC-MS analysis for a mixture of compounds, carry out a protocol for selected ion monitoring, and then determine a number of kerosene component classes using GC-MS. The first exercise analyzes a standard solution containing different compounds by using GC-MS, obtains characteristic ions, conducts library searching, calculates retention indices, and displays various extracted ion plots. Selected ion monitoring is then conducted based on retention time windows and characteristic ions for this sample. Kerosene is then analyzed by GC-MS to identify various classes of compounds using extracted ion plots to support compound class monitoring. The methods described in this report may be readily adapted to other kerosene components and other samples such as pesticides, essential oils, or other samples of interest.