A Belousov-Zhabotinsky (BZ) reaction which oscillates globally when mixed and support travelling excitation wave-fronts when not mixed.A liquid marble (LM) is a liquid droplet coated with a hydrophobic powder. We make LMs of 50\ce{\mu}L BZ solution droplets by coating them with a polyethylene powder. We insert a pair of electrodes in BZ LMs and measure an electrical potential difference between the electrodes. Oscillations of electrical potential are observed, with amplitude up to 100~mV and average period of 44~s. We freeze BZ LMs to -1\ce{^0}C and demonstrate that frequency of electrical potential oscillations in a BZ LMs cooled down halves from c.~23~mHz in in intact LM to c.~11~mHz in cooled LM. The frequency returns back to its intact state when the BZ LMs are warm up. Several cycles of frequency halving and doubling can be achieved.