To date, direct temperature-resolved mass spectrometry (DT-MS, a form of temperature-resolved, in-source pyrolysis mass spectrometry) has generally been used to provide qualitative views of the broad-band molecular-level characteristics of complex organic samples. In this paper low voltage electron impact (EI+) DT-MS is used to provide semi-quantitative information on molecular-level characteristics of marine particulate organic matter (POM) samples. This class of samples is analytically challenging for two main reasons. Firstly, it is difficult to obtain representative data sets in which sample sizes are sufficient for characterization. Secondly, marine organic matter samples contain many identifiable compound classes in conjunction with a substantial percentage of as-of-yet uncharacterizable material. As a first step toward quantitation, DT-MS analysis of selected standards was used to determine relative response factors of common compound classes identified in marine organic matter. These response factors were then used to quantify the relative contribution of the compound classes in two natural POM samples. The potential of DT-MS as a quantitative technique was then further explored by comparing DT-MS determinations of particulate organic carbon to chlorophyll ratios (POC/chl) in natural POM samples with the same ratios determined by elemental analysis and liquid chromatography (HPLC), a technique currently employed by marine chemists.