Barriers and coatings are commonly used as protective layers of consumables such as food and liquid packages1,2, however, currently harnessed conventional barrier layers are predominantly made from fossil-based polymers, with increasing global consumption causing concerns related to climate change. Therefore, bio-based barriers and coatings are urgently needed to reduce greenhouse gas emissions and our dependency on fossil-based raw materials. In this work, water dispersions of suberin, a natural polyester of birch bark with inherent hydrophobicity, were demonstrated as sustainable and green alternative materials for barrier layers in fiber-based packaging. Suberin fractions were isolated from birch outer bark using alkaline ethanol-water fractionation process, following by thermomechanical dispersing (55 – 75 ℃) to produce stable aqueous dispersions of suberin. They were further used in coating of paper and paperboard substrates using a pilot-scale coating line (Figure 1a). The impact of pH, temperature, addition level of stabilizer, and Ultra Turrax post-treatment on the dispersion stability, particle size and rheology were assessed. The aqueous suberin dispersions exhibited homogeneous particle size distribution in the range of 1 – 100 µm, and their shear-thinning behavior benefitted the pilot-scale coating process. Most importantly, the resulting suberin coated paperboard sample showed an excellent barrier against water vapor (18 g/m2/day), heptane vapor (below the detection limits), grease resistant (KIT number of 12), and oil penetration (24 – 168 hours). Therefore, the aqueous suberin dispersions are promising coating materials for barrier packaging applications, and their barrier performance is comparable to commercial barrier dispersions (Figure 1b).Keywords: suberin, aqueous dispersion coating, fiber-based barrier packaging, biopolyester, biodegradable