Abstract In previous work it has been shown that RbxWO3 and KxWO3 have anomalies in the resistance vs. temperature. The temperature at which the anomaly occurs is composition dependent, with a maximum near x=0.25. The superconducting transition temperature, Tc, also shows a minimum at this composition. On the other hand, CsxWO3 shows no anomaly in the resistivity, nor any dip in Tc as a function of composition. In order to further study this behavior, RbxCsyWO3 was investigated for x+y=0.28 and 0.24. The results show that the temperature dependent resistive anomaly and Tc scale linearly with increasing y.