Constructed wetland treatment systems are engineered systems that proved to be effective in removing of nutrients and suspended solids from polluted streams, mathematical models have been frequently used for sizing of engineered wetlands systems (EWs) because they are more accurately represent the liquid behavior in these reactors, among these models the first order models Reed and K-C* (Kadlec) models has already been used in the prediction of organic matter removal in EWs, but kinetic parameters estimation, calibration, and validation of these models have been little explored in the literature. In the present work, the operation data from a full scale EWs was used to develop design curves in order to be used as a tool for the prediction and control of wetland performance, this was done by estimating the kinetic parameters for Biochemical oxygen demand (BOD), Total suspended solids (TSS), Ammonia nitrogen (NH4-N) and Total Phosphor (TP) for the two 1st order models, this estimation was validated using the least square method. The two model’s implementation using the estimated kinetic parameters provide a comprehensive description of the organic removal processes as the model predicted the behavior of the tested sets of data with considerable accuracy, the prediction of the two models were almost identical for all tested constitutes types and values.