Two types of biomass: pine bark (PB) and wheat straw (WS) were co-pyrolysed with tetra pak waste (TPW) in fixed bed reactor. The blend ratios of 75 %wt PB to 25 %wt TPW and 75 %wt WS to 25 %wt TPW were analyzed. The investigations were performed using the reactor equipped with an innovative system where the sample is heated very fast from ambient to process temperatures. Co-pyrolysis products were collected as: liquid phase, wax and tarry compounds, condensed gases, solid residue (char and aluminum foil), and gaseous products. The multifaceted analysis included: products yields and mass balances for each studied samples, proximate and ultimate analysis of chars, the determination of char ignition and burnout temperature using thermal gravimetric analysis (TGA), chemical composition of pyro-gas by flue gas analyzers. The lower the burnout temperature were noticed for 75PB-25TPW and 75WS-25TPW chars than for TPW char. The effects of TPW addition to PB and WS were: i) reduction of char mass, as well as carbon, hydrogen and nitrogen contents in char; ii) lower mass of the resulting liquid phase; iii) increasing the yields of wax and tars retained in the water cooler; iv) increasing the yields of pyro-gas. Curves reflecting CO2 concentration in pyro-gas as a function of time had two local maximum.