An approach on how to formulate redundancy-free models for mathematical descriptions of complex chemical reactions is introduced. This is based on an automatically created redundant (generalized) model, which is formulated according to the complete reaction network. These redundancy-free models can be obtained as a result of either a step-by-step, or a one-step elimination of model parameters, with the help of sensitivity and interval analysis. An example of this procedure is demonstrated using n-decane isomerization. Starting with a 24-parameter in the redundant model, the redundancy-free model includes only 8 parameters.