Adhesion of polymers onto metal substrates is a task which has not been completely solved, especially in terms of long term applications and/or in humid or corrosive environments. The stability of the joint depends, in greater extent, on the surface of the substrate and the pretreatments performed on the parts that are in direct contact. In this work, bonding of overmolded thermoplastic polyurethane (TPU) on three types of steel pre-treated surfaces, namely, phosphate, adhesive primer and untreated cold rolled, was evaluated. The adhesion of the polymer on a preheated metal insert and on tempered samples was also analyzed. Surface and bonding strength analysis using confocal and atomic force microscopy (AFM), contact angle and mechanical tests were used in order to determine the best adhesion of the TPU on the metal substrates. Interesting results were obtained in terms of successful adhesion between the polymer and the metal, especially in the samples that were tempered and overmolded on a preheated insert.