What is the Best SIM card to use in Kiev
Internet access on mobile phones in Kiev and Ukraine is very cheap and reliable. Ukraine ranks 4th in the world for the cheapest mobile internet and in Kiev you won't have any problems finding free WiFi networks to connect to in bars and restaurants. What you don't want is to be landed with huge roaming charges, so make sure you turn off data roaming or better still purchase a local pre-paid SIM card with data and messaging from the many outlets across Kiev. Most staff in stores speak at least a small amount of English and will be a able to set you up in no time. The best pre-paid SIM cards in Kiev are Kyivstar and Vodofone Ukraine.
SIM cards in Kiev

Bring a spare phone with you to Kiev (Kyiv). Sim cards are really cheap and you can save yourself a lot of data usage (and money) by using a local SIM card. There are lots of places to purchase them from but be careful to check the tariffs.
WiFi Connectivity in Ukraine
Kiev (Kyiv) is a modern city with high technological skills. You will not necessarily need a local SIM card as you will have no problem finding WiFi connectivity, almost every restaurant, hotel, bar and cafe supports this.
Although you will not need a local SIM card, it might be a good idea to purchase one anyway. They are extremely cheap, easily available and will save you racking-up expensive call charges on your home phone.
If you are in the centre of Kiev you will easily be able to purchase local SIM cards from just about anywhere. The moment you set foot on a main street you will see many little kiosks.They sell everything you’d expect; drinks, magazines, cigarettes, snacks, and of course SIM cards. But for the best advice go into a dedicated store.