Abstract-This paper describes the computer-aided-design (CAD)-assited microwave characterization of coplanar waveguide (CPW) lines formed by ink-jet printed technology on flexible polyethylene terephthalate (PET) substrates. A spacemapping technique is used to link the measured results with simulations and the mapping is used to extract the electrical properties of the ink and supporting dielectric spacer employed during measurements. Results indicate that the losses in lines are predominantly due to the loss tangent of the substrate and the conductivity of the ink. Estimates of the conductivity of the ink and the dielectric constant of the spacer used during measurement were obtained as 2.97 × 10 7 2.97 × 10 7 2.97 × 10 7 S/m, and 1.79 respectively.