The production of fully biodegradable materials is receiving large attention in the research community and industrial sector as the way out to produce environmentally friendly products. Biodegradable polymeric materials are an important alternative because they diminish the consequences of plastic waste through composting. In this communication, the preparation and compatibilization of biodegradable blends of cellulose acetate (CA) with two water soluble polymers; polyvinyl alcohol (PVOH) and the bio-sourced hydroxyethyl cellulose (HEC) will be presented. Like CA, HEC is advantageously both biodegradable and bio-sourced. For that purpose, plasticization of CA and PVOH was conducted by melt extrusion using triacetin and glycerol, respectively, while a two-step method consisting in a premixing step of HEC with plasticizer in presence of water, followed by the melt processing of the swollen premix was used and led to the successful plasticization of this biopolymer. Plasticized PVOH-based blends proved to exhibit better processability and properties. The prepared blends were characterized in terms of morphology and thermo-mechanical properties. The quality of blend interface was enhanced by reactive compatibilization using maleic anhydride grafted-polylactide (MAgPLA). An original procedure was conducted using two extruders connected in a T-configuration to prepare various plasticized CA-PVOH blends compositions. This advantageous set up allowed for in situ plasticization of CA which significantly reduces its thermo-oxidative degradation. The water-response of these blends was evaluated to settle on their potential as new water-dispersive biodegradable materials. Keywords: Cellulose acetate; Polyvinyl alcohol; Hydroxyethyl cellulose; Plasticization; Biodegradation; Biopolymer; Reactive compatibilization