Transparent and stable silver ink based on silver-ethanolamine-formate complex (SEFC) was formulated, wherein both ethanolamine and formate species act as in-situ complexing solvent and reducing agent. as formulated particle-free SEFC-based inks (22.44 wt%Ag) were applied on glass and polyimide (PI) substrates, followed by annealing the deposited films with either thermal heating at 180 degrees C for 30 min or microwave-plasma irradiation. The former resulted in conductivities of 3.5 x 10(4) S/cm (on PI) and 9.1 x 10(4) S/cm (on glass), and the latter yielded 8.3 x 10(4) S/cm (on PI) and 1.4 x 10(5) S/cm (on glass) which is the same order of magnitude of bulk silver (6.3 x 10(5) S/cm). (C) 2016 Elsevier B.V. All rights reserved.