The national currency in Kazakhstan is tenge (KZT).
Goods and various services are allowed to be paid for in tenge only, therefore, it is better to think in advance about having some cash. Russian roubles, US dollars, Euro, and some other currencies you can exchange in the banks and official exchange offices, where, as a rule, there are more profitable exchange rates.
In large cities exchange offices work 24/7; also there is a lot of ATMs. Bank cards (Visa, Master Card, Euro Card) for payment are accepted almost in all shopping malls and hotels. However, if you plan a trip outside the city, you had better have some cash.
In case amount of the capital flow exceeds ten thousand US dollars then it is subject to mandatory customs declaration (except the capital flow from the the member states of the Eurasian Customs Union).