Complex coacervation is a liquid-liquid phase separation that occurs between two oppositely charged macromolecules and leads to the formation of a concentrated phase called coacervates. The formed coacervates are proposed as efficient encapsulating agents for bioactives. Here, we studied the specific case of heteroprotein complex coacervation (HPCC) between positively charged Lactoferrin (LF) and negatively charged β-lactoglobulin (β-LG). We aimed to determine the sensitivity of LF/β-LG complex coacervation process to ionic strength and subsequent properties of formed coacervates. Dialysis experiments showed the very high sensitivity of LF/β-LG complex coacervation to ionic strength. Complex coacervation only occurred at ionic strength values lower than 30 mM. Furthermore, in an environment of low ionic strengths, there is a small window where complex coacervation between the two proteins is favoured as assessed by ITC measurements. The interaction strengths deduced from the ITC profiles in the range of 3-5 mM NaCl are higher than in the absence of salt. Hence, addiction of a low salt concentration promoted the interaction between the two proteins leading to a higher coacervation yield. These results shed new light on the mechanisms governing the complex coacervation in heteroprotein systems