Ukrainian President Volodymyr Zelensky joined airline staff and victims’ relatives at a ceremony in Kiev's Boryspi Airport.
All 176 people on board a Ukraine International Airlines flight died when their plane was hit by a missile in Tehran.
Ukraine says Iran should compensate the victims' families and punish those responsible.
Iran says the incident was a mistake, and that it has no plan to send the plane's flight recorder abroad for separate analysis.
