The synthesis and characterization of polymer-stabilized silver nanoparticles (Ag NPs) for water-based silver inks are studied. In order to synthesize Ag NPs with spherical shape, the conventional polyol processes require an excess of poly(vinyl pyrrolidone) (PVP) (10 ~ 1000 times than AgNO3) and therefore result in low productivity per reactor volume. In this study, poly(acrylic acid) (PAA) with carboxylic acid group was used instead of PVP. Even at less molar ratio of PAA to AgNO3 (< 2), the spherical Ag NPs with average size of 30 nm were successfully synthesized at 100 gram-scale with high reaction yield of 90%. Furthermore, the Ag NPs were dispersed into alcohol-based solvent and then patterned into metallic lines through inkjet printing technology.