Kyzyltuz (; ) is a salt lake in Akkuly District, Pavlodar Region, Kazakhstan.
The lake is located to the west of Malybay village, about west of the Russia-Kazakhstan border. Akkuly, the district capital, lies to the southwest.
Kyzyltuz is part of the Irtysh basin. It lies in a tectonic depression of the Kulunda Plain. Lake Borli lies to the northwest, Kazy to the WNW, Zhaltyr and Malybay to the ESE, Sharbakty to the south, and Seiten to the NNW.
The lake has a striking red color. This is in clear contrast with the other lakes in the area which display blue or green hues. The northern shore of Kyzyltuz is rocky.
Lake Kyzyltuz is surrounded by steppe vegetation. Reeds grow in some stretches of the lakeshore.