If you intend to stay in Ukraine for more than 90 days you do need a visa.
If you intend to stay in Ukraine for up to 90 days within a period of 180 days you do not need a visa for tourist or business trips if you're citizen of: Albania, Andorra, Antigua and Barbuda, Argentina, Armenia, Australia, Austria, Azerbaijan, Bahrain, Belarus, Belgium, Bosnia and Herzegovina, Brazil, Bulgaria, Canada, Chile, Colombia, Croatia, Cyprus, Czech Republic, Denmark, Dominica, Ecuador, Estonia, Finland, France, Georgia, Germany, Greece, Hungary, Iceland, Israel, Italy, Kazakhstan, Kuwait, Kyrgyzstan, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Marshall Islands, Moldova, Monaco, Mongolia, Montenegro, Netherlands, New Zealand, Northern Macedonia, Norway, Oman, Panama, Paraguay, Poland, Portugal, Qatar, Romania, Russia, Saint Kitts and Nevis, San Mari, Saudi Arabia, Serbia, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, Tajikistan, Turkey, UAE, United Kingdom, Uruguay, USA, Uzbekistan, Vatican.
Required documents to be presented upon arrival to Ukraine:
Valid passport (on the planned date of departure from Ukraine, your passport should have at least another 3 months validity).