The catalytic co-gasification of rubber seed shell (RSS) and high density polyethylene (HDPE) mixture is investigated in a bench scale fixed bed system known as high throughput micro reactors (HTMR) system at different reactor temperature of 600 - 800 °C in order to study the effects on performance parameters such as gas and char yield, syngas yield and product gas composition. The operating temperature is selected based on the optimum conditions found from the previous study on the thermogravimetric analysis equipment coupled with mass spectrometer using these feedstock. The constant process variables used in the HTMR system are RSS particle size range of 0.100 - 0.150 mm, HDPE particle size range of 0.355 - 0.500 mm, and percentage of HDPE in the mixture of 20 weight. The feeding rate of 2 g/h is carried out in the system. © 2016, AIDIC Servizi S.r.l.