The solid-solid reaction between zirconia and carbon under flowing argon produces zirconium carbide via the intermediate formation of an oxycarbide ZrC0.84O0.06. In the temperature range 1623-1823 K, its final transformation into carbide is slow. The reaction producing the oxycarbide obeys the kinetic law between the degree of conversion alpha and time : F(alpha) = 1 - (1 - alpha)(1/3) = K e(-E/RT) t, associated with an activation energy of 208+/-15 kJ.mol(-1). This reaction occurs via two solid-gas reactions : ZrO2 + 0.84 CO = ZrC0.84O0.06 + 1.39 O-2 and 2.78 C + 1.39 O-2 = 2.78 CO.The oxycarbide appears on the surface of the oxide whose grain shape is not modified.