The Moscow terminal for trains to/from Kiev and several eastern and central european destinations including Belgrade, Zagreb, Bucharest, Budapest, Prague, Vienna, and even Venice, Kiev Station is about 5km west of the Baltschug Kempinski Hotel.
By taxi
If you take a taxi to the hotel, the drive should take around 20 minutes and cost $15-20. Alternatively, order a transfer with a driver to meet your train here.
By metro
From Kievskaya Metro Station, which is connected to the mainline station, take the dark-blue line two stops east to Ploshchad Revolyutsii, change to the dark-green line, and travel south one stop to Novokuznetskaya, which is about 500m from the Baltschug Kempinski Hotel.
