A novel lab-scale reactor system designed for investigation of olefin polymerization reactions using homo- and heterogeneous catalysts is introduced. The high inert atmosphere level of the system is based on stainless-steel lines and cylinders, a nitrogen/vacuum technique, and removable reactants chambers which are packed in a glove-box. The solvent is transferred straight from the distiller through the reagents' containers into the reactor. The reactor is equipped with an ethylene pressure/mass flow and two temperature-control systems. Data acquisition is based on a personal computer and software for monitoring and data storage. The results of versatile ethylene copolymerization with cyclopentene, cyclooctene, and cyclododecene with this reactor system are discussed.