The undesirable polymerization of unsaturated species yielding gums and deposits is likely to disturb many processes or systems using hydrocarbons, in particular motor engines, industrial production of olefins, or gas turbines units. To allow the determination of a safe margin of operation, a detailed chemical kinetic approach is proposed to develop a model of reaction applicable in the low-temperature/high-pressure range with very low conversion rate. A model for a mixture of alkanes, olefins, conjugated diolefins, and alkynes is described and used to simulate the practical case of a gas turbine fed with a petrochemical gas. The factors influencing the polymerization rate are analyzed. The presence of diolefin, especially propadiene-like ones, is a critical parameter. Alkynes also increase dramatically the formation of gums. A coupling effect between diolefins and monoolefins or alkynes is established. Temperature is the most sensitive reactor parameter. Correlations are proposed between the rate of the polymer formation and the composition of the mixture.