Multi-input multi-output (MIMO) models of a twin-screw co-rotating extruder for thermoplastic vulcanizate (TPV) are developed using the process identification techniques. The process inputs are screw speed (SS) and barrel temperature (WT). The three outputs are motor load (ML), melt temperature (MT), and melt pressure (MP). Two appropriate rubbers for TPV applications with different physical and mechanical properties are used for the experimentation. The process model is obtained from the experimental input-output data using various identification techniques such as least squares and prediction error. Recursive online model identification is performed on the process to update the model parameters in real time. To perform the identification studies, the process data was transferred via OPC server from the local PLC (Programmable Logic Controller) to the Advanced Control and Identification toolbox in MATLAB software. The effect of rubber properties and two curative agents (Peroxide and Phenolic) in the TPV experiment are studied on the final identified models. This comprehensive model identification study provided sufficient accurate models for further model based process analysis and control for TPV applications. POLYM. ENG. SCI., 50:1168-1177, 2010. (C) 2009 Society of Plastics Engineers