The effect of the addition of the triazoline derivative 1 on the radical polymerization of styrene and some methacrylates is discussed. The polymerization of styrene in the presence of 1 exhibits the characteristics of a controlled radical polymerization such as a linear time-conversion development and increasing molecular weights versus conversion. Additionally, even monomers other than styrene, namely methacrylates, can be polymerized in a controlled fashion. Furthermore, the properties of the isolated PS and PMMA samples were studied. It will be shown, that polymers obtained by controlled radical polymerization in the presence of 1 possess triazolinyl end-groups and the degree of end-functionalisation will be estimated. To demonstrate the ability of the polymers to reinitiate, chain extension experiments were performed on our PS-samples.