Hundreds of people gathered in central Kiev on Saturday to show support for an independent cable TV channel that claims it is being censored after several operators suspended its broadcasts.
Protesters in the Ukrainian capital held banners with slogans such as "Stop censorship" and "TVi is the last frontier of freedom."
Similar demonstrations were held in Kharkiv and other cities.
The action comes after TVi was taken off air in eleven regions across the country, in a move that it says was prompted by pressure from the authorities.
TVi is critical of President Viktor Yanukovych and his government.
But operator Triolan denied it had come under pressure, citing internal issues for the decision.
A number of high-profile opposition figures, including Arseniy Yatsenyuk, leader of the Front for Change party, joined the protest in Kiev.
The authorities have made no comment as yet.