The stress‐temperature behaviors of RuO2 thin films on (100) Si were investigated by measuring the deflection of film‐coated substrates in situ during thermal cycling between 25 and 700 °C. The average biaxial elastic modulus [E/(1-ν)] and thermal expansion coefficient (α) of RuO2 thin film were also determined using the stress‐temperature curves of the films on both (100) Si and quartz substrates. For this study, RuO2 thin films were deposited by rf magnetron reactive sputtering at the substrate temperature range of 25–450 °C. As‐grown thin films deposited between 300 and 450 °C showed different stress‐temperature behavior, which was caused mainly by the microstructure of the thin films. The values of [E/(1-ν)]RuO2 and αRuO2 were calculated to 3.09×1011 Pa and 10.47×10-6/°C, respectively, in the range of 350–600 °C. The αRuO2 obtained from the stress data was compared with the α value calculated from the thermal expansion coefficient, αa and αc, of RuO2 single crystal. Both values were found to be in good agreement. © 1996 American Institute of Physics.