This paper on core samples collected from the Triassic Montney Formation tight gas reservoir in the Western Canadian Sedimentary Basin (WCSB) illustrates that operationally-defined S1 and S2 hydrocarbon peaks from conventional Rock-Eval analysis may not adequately characterize the organic constituents of unconventional reservoir rocks. Modification of the thermal recipe for Rock-Eval analysis in conjunction with manual peak integration provides important information with significance for the evaluation of reservoir quality. An adapted method of the analysis, herein called the extended slow heating (ESH) cycle, was developed in which the heating rate was slowed to 10°C per minute over an extended temperature range (from 150 to 650°C). For Montney core samples within the wet gas window, this method provided quantitative distinctions between major organic matter (OM) components of the rock. We show that the traditional S1 and S2 peaks can now be quantitatively divided into three components: (S1ESH) free light oil, (S2aESH) fluid-like hydrocarbon residue (FHR), and (S2bESH + residual carbon) solid bitumen (more refractory, consolidated bitumen/pyrobitumen).