The thermal and mechanical properties of polystyrene (PS) modified with esters derivatives of 3-phenylprop-2-en-1-ol were investigated. The influence of the content of esters on the glass transition temperature, dynamic mechanical properties, flexural properties, hardness and thermal stability of PS has been examined. It was found that the PS/ester compositions were characterized by lower stiffness, lower values of T _g, lower hardness, lower stress at break, lower thermal stability and higher values of tg delta height and strain at break as compared to pure PS. The obtained results proved that esters derivatives of 3-phenylprop-2-en-1-ol can find their place as an environmentally friendly, external plasticizers of PS.