In this study, local sensitivity analyses are performed on a selected pyrolysis model. The specific scenario considered is the anaerobic thermal degradation of a fictitious homogeneous semi-transparent non-charring material (simulating a thermoplastic) exposed to heat flux levels leading to thermally thin and thermally thick material responses. A methodology is presented, which involves the complex-step differentiation approach, to compute the first-order sensitivity coefficients of relevant model outputs with respect to the inputs, i.e. the material properties. Normalization schemes are also introduced so that sensitivity coefficients can be directly compared among the different conditions considered. Unlike previous efforts aimed at understanding the effects of material properties on the predictions of pyrolysis models, the approach described herein is systematic and robust and provides sensitivity coefficients that are dynamic; that is, sensitivity values are given as a function of time for the entire pyrolysis process. The information provided by the sensitivity analyses presented here can help reduce the complexity of a given pyrolysis model for a specific application.