Ukrainian Defence Minister Oleksii Reznikov gave Britain the thumbs up as he took a ride in what he said was the first British Challenger 2 main battle tank to arrive in Ukraine.
Britain said in January it would send 14 of the tanks to Ukraine, which is preparing for a possible counter-offensive against Russian forces that invaded 13 months ago.
Reznikov wrote on Twitter that the tanks had "recently arrived in our country" and posted a video that showed him sitting in one of a long line of tanks in an open field, all of them flying Ukraine's yellow and blue flag.
"It was a pleasure to take the first Ukrainian Challenger 2 MBT (main battle tank) for a spin," Reznikov wrote. "These fantastic machines will soon begin their combat missions."
In the video, he gave the thumbs up sign and thanked British Defence Secretary Ben Wallace for the tanks.
"Marvellous, Ben," he said in English. "It's...very good stuff. Thank you very much from Ukraine to the United Kingdom."
Germany's defence ministry said on Monday that 18 Leopard 2 battle tanks and 40 Marder infantry fighting vehicles had also arrived in Ukraine.