Effects of an Ag2O addition in Y0.9Ca0.1Ba2Cu4O8 on the contact characteristics of Y0.9Ca0.1Ba2Cu4O8/Ag interfaces have been investigated by the measurement of contact resistivity. The lowest ohmic‐contact resistivity about 4.55×10-5 Ω cm2 at 300 K and less than 10-8 Ω cm2 below Tc for Ag2O‐free system are observed by annealing at 600 °C for 1 h under one oxygen atmosphere. With addition of 25 wt % Ag2O in Y0.9Ca0.1Ba2Cu4O8, the optimal annealing condition for the lowest ohmic‐contact for Y0.9Ca0.1Ba2Cu4O8/Ag interface can be achieved without any thermal annealing just by the addition of 25 wt % Ag2O in Y0.9Ca0.1Ba2Cu4O8. These results indicate that the addition of Ag2O can upgrade effectively the characteristics of Y0.9Ca0.1Ba2Cu4O8/Ag interfaces to get the better ohmic contact even without annealing, resulting in a lower annealing temperature and contact resistivity. © 1994 American Institute of Physics.