A review of the techniques concerning the Molecular Identification of Organic Compounds in the Atmosphere is presented. An organic compound is fully identified only if its molecular structure is entirely known, including its isomeric and spatial (stereo) configuration. The first type of problem is when organic compounds need to be inventoried for the purpose of establishing a budget. Generally, such budgets are required to gain insights into specific properties of the compounds, such as their optical properties for the global energy budget or their volatility for SOA precursors. In such cases, the organic compounds do not need to be individually identified, but only quantified on the basis of this common property.