Plasma electrochemistry is an emerging technique for nanomaterial synthesis. The present study reports the preparation of yttrium oxide nanoparticles via a simple, environmentally benign, microplasma-assisted process operated in pin-to-liquid configuration under ambient atmospheric conditions using yttrium nitrate aqueous solution as the precursor. The plasma-liquid interaction was monitored in-situ by optical emission spectroscopy. The morphology, structure and chemical composition of the obtained products were examined by complementary analytical methods. It was demonstrated that high purity crystalline Y2O3 nanoparticles with adjustable sizes can be fabricated via a two-step method: plasma electrodeposition of yttrium hydroxide followed by heat-treatment at various temperatures. A micro-plasma array design was proposed for the process upscaling towards industrial level production. Moreover, possible mechanisms for plasma-assisted yttrium hydroxide precipitation were discussed by correlating optical emission spectroscopic studies, plasma kinetic analysis and the precipitation equilibrium. As a proof-of-concept, this process offers a facile, environmental friendly and scalable route for rare-earth oxide nanomaterial synthesis. (C) 2017 Elsevier Ltd. All rights reserved.