The remarkable progress in nanotechnology has extended the application of inorganic nanoparticles (NPs) in the agriculture sector, as both economically sustainable and environmentally sound alternatives. Root knot nematodes are undoubtedly a foremost problem of agriculture and research strives to develop effective materials to tackle this issue. Herein, the microwave-assisted selective polyol synthesis of different compositions of Cabased NPs, Ca(OH)2, Ca(OH)2/CaCO3 and CaCO3 is reported and the products were evaluated as nematicides and pH adjusters. Two precursors (CaCl2 and Ca(NO3)2) and three polyols (1,2-propylene glycol (PG), tetraethylene glycol (TEG), polyethylene glycol (PEG 8000)) that differ in their red/ox potential have been utilized to provide selectivity over composition. Based on the utilized polyols, NPs are produced as inorganic/organic hybrid formulations with a biocompatible organic coating that provides increased colloidal stability and controlled release of active components. Characterization of NPs has been carried out by XRD, TGA, FTIR, TEM and pH-metry. Each composition exhibited different pH changing ability, an essential feature for agrochemical applications. The in vitro nematicidal activity of Ca(OH)2, Ca(OH)2/CaCO3 and CaCO3 NPs was evaluated on second stage juveniles (J2) of two Meloidogyne species (Meloidogyne incognita & Meloidogyne javanica) based on nematode paralysis experiments. Results unveiled nematicidal activity for all evaluated Ca-based NPs, while Ca(OH)2 and CaCO3 NPs appeared to be the most and the least effective one, respectively. The nematicidal effect appears to be boosted by the release of [OH]anions, as indicated by pHmetric measurements, displaying the crucial role of [OH]anions in their nematicidal activity.