Bio-based materials have superior properties in terms of health and environmental friendly as compared withsynthetic materials. This makes bio-based materials a good alternative for the future. The sensitivity on this issuehas increased even more with the natural disasters that have occurred in recent years and the depletion of resources.In this study, it was aimed to develop alternative bio-based material foams from wastes of paper mills to petroleum based foams. The mixtures of black liquor and pine bark as the paper mill wastes were selected as the mainmaterials in the production of bio-foams. The changes in the foam structure were determined by adding with different rates of Tween 80 and protein foaming agents (2 g and 4.4 g). The structural and chemical properties ofthe foams were determined using scanning electron microscopy (SEM) and Fourier Transform Infraredspectroscopy (FTIR), respectively. In SEM analysis, the maximum cell size was found as 55.24 µm for the F-3 (2 g protein foaming agent) sample, while the minimum cell size was 15 µm for F-1 (4.4g protein foaming agent) sample. The maximum and minimum cell size and wall thickness were determined respectively as 5.93 µm for F 2 (4.4g Tween 80) sample and 3.66 µm for F-4 (2 g Tween 80) sample. Bio-foam from kraft liquor has shown a promising success with its foaming features and adequate porous structure for using as an insulation material. By replacing petroleum-based foams with bio-based foams, a new value-added alternative material can be produced from paper mill wastes.