The Royal Zoological Society of Scotland (RZSS) has placed male bear Arktos in with female Victoria at its Highland Wildlife Park near Aviemore.
Polar bear cubs were last born in the UK almost 25 years ago.
Arktos is one of two male bears at the park at Kincraig in the Cairngorms National Park. The pair could remain together for about two weeks.
Arktos will eventually return to an enclosure he shares with the other male, Walker.
RZSS said captive breeding was an important part of a wider effort to conserve polar bears, which are classified as "vulnerable" on the International Union Conservation of Nature's Red List of Threatened Species.
However, animal welfare organisations OneKind Scotland and Born Free Foundation have said tackling climate change to better protect wild bears should be the focus of conservation efforts rather than captive breeding.
RZSS, which also manages Edinburgh Zoo where efforts have been made to breed giant pandas, said Arktos and Victoria have mated several times so far.
The society said the pair would live together for the next week or two "mimicking what would occur naturally in the wild".
Vickie Larkin, head carnivore keeper at the park, said the pair had appeared to have bonded well since being introduced.
She said: "Both polar bears have really warmed to each other and all the signs are really positive.
"From the first moment they met, Arktos has been really gentle with Victoria and their bond has been immediate.
"Polar bear breeding is inherently complex as the species are induced ovulators, meaning that the female only releases an egg after initial mating occurs. They also practice delayed implantation, where the egg doesn't implant into the uterine wall until some months later."
Ms Larkin added: "If successful, Victoria will not fall pregnant until August to September time.
"Other key stages are her entering the birthing den in October to November and potentially giving birth in December to January. Any cubs would then not come out of the birthing den until March to April 2017."
Arktos arrived at the park in April 2012 from a zoo in Hannover, Germany.
When being given health checks, park staff talk to Arktos in German, the language he heard when he was in the zoo in Hannover.
Victoria, who was brought to Scotland from Aalborg Zoo in Denmark last year and is kept in an enclosure about a mile away from the males, previously raised cubs in 2008.
Polar bears involved in a Scottish captive breeding project are sharing an enclosure and mating.