Essential oil containing ALG/CG nanoparticles. •Alginate/cashew gum nanoparticles were used for encapsulation of an essential oil•Particles have sizes in the range 223–399nm and zeta potential from −30 to −36mV•FTIR provided evidence of oil encapsulation and biopolymer and LS oil presences•X-ray and TGA/DSC revealed the good miscibility of both alginate and cashew gum•A release profile over 30h was achieved, whereby circa 95% of oil was released Alginate/cashew gum nanoparticles were prepared via spray-drying, aiming at the development of a biopolymer blend for encapsulation of an essential oil. Nanoparticles were characterized regarding to their hydrodynamic volume, surface charge, Lippia sidoides essential oil content and release profile, in addition to being analyzed by infrared spectroscopy (FT-IR), thermal analysis (TGA/DSC) and X-ray diffractometry. Nanoparticles in solution were found to have averaged sizes in the range 223–399nm, and zeta potential values ranging from −30 to −36mV. Encapsulated oil levels varied from 1.9 to 4.4% with an encapsulation efficiency of up to 55%. The in vitro release profile showed that between 45 and 95% of oil was released within 30–50h. Kinetic studies revealed that release pattern follow a Korsmeyer–Peppas mechanism.