Is the use of "Kiev" (or other Russian-based spelling) considered offensive in Ukraine?

Kiev predominantly speaks Russian and maintains Russian culture. Ukrainian language (or Surzhyk) is mostly spoken in western and partially central Ukraine. Thus, it might cause some minor dissatisfaction in the respective regions (or among those who moved to Kiev from them), although in Kiev and the rest of Ukraine there is no evident reason for it to be offensive. At some point, it’s even vice versa: Kievans find the imposement of Ukrainian language offensive.

Living since several years in Kyiv and hadnt any problem/issue with speaking russian.By the way – also not in Lviv or western ukraine…there will be more such a problem that people understand russian, but may not answer in russian and explain after more;)! But – Kyiv is the official ukrainian writing in the latinic ABC.By myself f.e.,I use in my official letterhead the wording “Kyiv” for the english part.
If you search f.e.at railway-page uz.gov.ua/english version “Kiev”, you will even not find the railway station;-)!
So you see – its mixed here – officially ukrainian is the state language and russian is the economical leading language…but even at home the most people are speaking a mixture of both,depending on their local origin.

“Kiev” is the only one I use living in Ukraine because the life around takes place in Russian except rare cases where the government roughly forces us to use Ukrainian. It is just my example though, other people are used to and prefer Ukrainian.

The same person who edited your question used to edit my earlier Ukraine answer, with a similar edit of city name: Kharkov vs. Kharkiv (I edited my answer back, but I retained his edit of the question itself). The fun fact is that I live in Ukraine, and the one who edits and enforces Ukrainian spelling moved to work abroad.

Another ex-Ukrainian downvoted this answer of Ukrainian local. Such excessive over-Ukrainianity is a result of 2014 events. So in general “Kiev” and other cases of Russian spelling are not offensive. Neither they are considered rude, or even incorrect. Be sure that even editor of your questions was perfectly aware of your spelling being proper, he just used his chance to do the modification at his own liking. However once in a while you can meet people who is aggressively an indecently insisting on Ukrainian spelling. Among real life people its well under 1%, as long as you asked for percentage estimate.

You seem to be one of those who have approved the edit (unfortunately, the post has been vandalized by another user since then), so I guess (correct me if I’m wrong) this question’s goal is primarily to confirm your original thought.

“Is it offensive?” question seems to be subjective because it can’t be measured. I would say yes, someone else would say no, and we end up in a “word against word” battle. So let me focus of facts only.

Official name of Kyiv. According to UNGEGN (United Nations Group of Experts on Geographical Names), the only possible English-language transliteration is “Kyiv“.
The same source confirms the proper spelling for Donets’k, Luhans’k, Kharkiv, and several others.

Kyiv in other languages. Besides “Kiev”, there are other spellings, including “Kiew”, “Kijów”, “Kænugarður” and even 《基辅》, pronounced — believe it or not — [ji-fu]. When visiting countries where this name is accepted, everyone would understand you, despite the fact these names are not internationally-accepted.

People’s perception. Indeed, spelling “Kiev” is a direct transliteration of “Киев”, the Russian word for Kyiv, and many Ukrainians (not all, however) associate this with the Russian occupation that happened in the past and the armed invasion and partial occupation that occurs at the moment.

The following photo shows the very process of russification. “Little green men” in unmarked uniforms on a military truck “enforce” the Russian spelling of a road sign at the entry to the occupied Donets’k city by removing the “soft sign” so that «ДОНЕЦЬК» became «ДОНЕЦК».

Most obviously, this produces resistance against the “Russian-based” spelling of toponyms among the Ukrainians. Like myself.

Many Russian officials also insist on using an incorrect spelling “the Ukraine”, too.
This, multiplied to the fact that many Ukrainians speak bad English, don’t simply care, or actively refuse to recognize Ukraine as a country, has a certain effect, as shown in JonathanReez♦’s answer.

More to go. Having several names for toponyms (for various historic reasons) happens in other countries, too: Burma/Myanmar, Cambodia/Kampuchea, Mumbai/Bombay, Munich/München/Monaco, Beijing/Peking, Saigon/Ho Chi Minh City, Bangkok/Krungthep Mahanakhon, Falkland/Malvin Islands, to name a few.

A Traveler’s Rule of Thumb (mind you, we are at Travel.SE). A traveler should always consider the historical and cultural aspects in order to avoid being perceived as an ignorant person (or, in boundary cases, as an enemy’s agent).
However, there is no problem if a foreigner uses Russian as their way of communication. Check this question for further details: What is the main spoken language in Kiev: Ukrainian or Russian?

Also, related: Does anyone want Ukraine to be called “the Ukraine”?

Googling for "kiev" site:.ua vs. "kyiv" site:.ua shows that both options coexist peacefully. Most Ukrainians are not proficient English speakers and don’t really care about minor intricacies of foreign spelling. .

So no, nobody cares which way you spell it. Source: traveling to Ukraine several times as a Russian speaker.