The effects of calcium content on the discharge characteristics of calcium lanthanum chromite (CaxLa1-xCrO3) thick-film cathodes were investigated for dc-type plasma display panels. To produce fine-grained powder, a calcium content of less than 0.4 is recommended. Powders with a calcium content of less than 0.2 showed perovskite single structures, while those with x > 0.4 produced a two-phase structure that contained grains with different calcium ratios. Both the minimum breakdown voltage and the minimum sustain voltage were constant values independent of the calcium content. Changes in the current-induced voltage due to variations in the resistivity of the powder were small. At a particular applied voltage, cathode films with a calcium content of less than 0.6 were much brighter than films with a content of more than 0.8. A high luminosity was produced for calcium content of 0 and especially 0.6. Based on these results, a calcium content of 0.2 is best from the standpoint of having a low driving voltage, high brightness, and good uniformity, while a calcium content of 0.6 is best from the standpoint of having low discharge voltage and high luminous efficiency.