We study the oxidation dynamics of thiosulfate ions by hydrogen peroxide in the presence of trace amounts of copper(II) using the reaction temperature as a control parameter in a continuous flow stirred tank reactor. The system displays period-doubling, aperodic, and mixed-mode oscillations at different temperatures. We are able to simulate these complex dynamics with a model proposed by Kurin-Csorgei et al. The model suggests that the Cu2+-containing term is not essential for the observed oscillations. We find small-amplitude and high-frequency oscillations in the catalyst-free experimental system. The reaction between H2O2 and S2O32- contains the core mechanism of the H2O2 S2O32--Cu2+ and H2O2 S2O32--SO32- oscillatory systems, while the Cu2+ and SO32- modulate the feedback loops so as to strengthen the oscillatory dynamics.