The veteran campaigner died on Thursday after battling a long term illness.
Mr MagLochlainn was a member of the SDLP and volunteered in the Mid Ulster area before moving to south Belfast. He was the first openly gay representative in a Northern Ireland political party's executive.
Mr MagLochlainn was a prominent activist and was president of the Northern Ireland Gay Rights Association for over 20 years.
Last year he was presented with an award from Belfast Pride for his years of dedication to the gay rights movement.
SDLP Party leader Alisdair McDonnell described Mr MagLochlainn as a "wonderful human being".
"He was kind and generous and very passionate about his politics, very passionate about gay pride and we'll all miss him," he said.
He was a democrat, an internationalist, a Christian citizen and a proudly gay, proudly Irish man who wanted to make a difference - for difference - and he did.
Mark Durkan, SDLP
SDLP Foyle MP Mark Durkan expressed deep sadness at the death of his party colleague and friend of 30 years.
"PA had a warm good nature, deep empathy and an extensive interest in public affairs and world events," he said.
"He brought acute logic to his analysis and wry humour to his argument. He believed passionately in education, democratic debate, respect for diversity and human rights.
"He gave a proud and distinctive contribution to the cause of gay rights and brought that same articulate understanding to challenge other prejudices and injustices as well."
He continued: "While resolutely proud in every aspect of his own identity he used self-deprecating humour and disarmed the presumptions of others with sensitive understanding wrapping his unapologetic logic.
"PA was a committed political activist who deplored violence and the denial of any human right. He was a great campaigner and he was great company."
Mr Durkan extended his sympathy to his partner Barry and the MagLochlainn family.
PA was a resolute and able defender of the rights of all people to live their lives free from discrimination or harassment.
Michael Wardlow, Equality Commission NI
Michael Wardlow, Chief Commissioner of the Equality Commission for Northern Ireland, also paid tribute to Mr MagLochlainn and expressed his sympathy to his family.
"He championed the rights of gay people before there was legislation in place to protect those rights and made an important contribution to the improvement of the lives of many people in Northern Ireland," he said.
Alliance Party Vice Chair Cllr Andrew Muir knew Mr MagLochlainn for many years and described him as "inspirational".
"The passion he demonstrated throughout his life motivated me to battle for a shared society inclusive of all regardless of sexual orientation," he said.
His tireless work and the respect that so many had for him will be his legacy.
Andrew Muir, Alliance Party
He added: "He showed a lot of courage and was very outspoken on the issues that mattered most to him. I hope that future generations will be inspired by him."
He will be at O'Kane's funeral parlour in Donegall St on Thursday from 3pm onwards for people to pay their respects.
Those who wish to celebrate Mr MagLochlainn's memory are asked to gather there on Thursday afternoon.
His funeral will take place in his hometown of Dungiven, Co Derry on Saturday.