Double emulsion technique (W-1/O/W-2) was used to achieve PLA (polylactic acid)-based microparticles loaded with thymol (hydrophilic antibacterial active) with high encapsulation efficiency (>90%) that was later released in water in controlled fashion. In order to enhance the release of thymol from semicrystalline slow degrading PLA matrix, pores were introduced into the particles by incorporating minute quantity of essential oils (EOs) such as castor, mustard, olive and coconut oils of varying viscosity (from 128 to 13mPaS). Strikingly, it was found that the pore size of microparticles (pore size 1.2-0.53 mu m and specific surface area 7.5-2.1m(2)/g) has been influenced by the viscosity of EOs. The plausible mechanism of formation of pores using EOs was also explored. As expected, the release rate of thymol did get accelerate with the increase in pore density and its release mechanism can well be explained with the help of power law model. In addition to that, these porous particles were demonstrated to act as an effective carrier for continuous delivery of thymol with enhanced inhibitory activity probably due to synergistic action of EOs and thymol. Therefore, EOs employed here served dual purposes. These PLA-based microparticles composed of completely natural ingredients can be exploited as active food packaging material to prolong the shelf life of food.