The reaction kinetics of cyclopentadiene (CPD) dimerization is studied using differential scanning calorimetry (DSC). Both dynamic and isothermal reactions are investigated. The experimental data were fit to a second order autocatalyzed reaction, taking into account the effect of elevated pressure on concentration which results from heating the easily volatilized reactant mixture in a sealed DSC pan. The rate constants and associated activation energies are obtained from the kinetic model, as well as from a model-free method. The results from the modeling with and without pressure effects are compared with one another and literature data.