A South Australian state high school has marked Wear It Purple Day, Australia’s national day supporting LGBT youth, by its entire student body signing a pledge to not use the word in a derogatory manner going forward.

Over 800 students at Wirreanda High School in the Adelaide suburb of Morphett Vale signed the pledge on Friday – becoming the second school to do so in the state.

The students all signed a banner with the slogan, ‘Pledge – It’s not okay to say “it’s gay.”

The school also gave out cupcakes to celebrate the initiative.

The pledge has been praised by openly gay Australian politicians at both a state and federal level.

South Australia’s Communities and Social Inclusion Minister Ian Hunter said he was 'immensely proud' of the Wirreanda students for taking a stand.

‘When I was growing up it never would have happened but it would have made my life so much easier," Hunter told Adelaide Now.

‘Having people come out and say they're not going to tolerate … the derogatory use of the word gay is a really powerful thing.'

Hunter said he hoped students at other schools would make similar pledges but said students should be the drivers of those efforts.

Australian Finance Minister, Penny Wong, who this year became a mother with her long term partner Sophie Allouache, told the website that the students should be ‘wholeheartedly commended.’

‘Their willingness to stand up for values so important to our community - respect, tolerance and equality - is heart-warming.’

Another Adelaide high school became the first to institute a similar measure earlier this year following the establishment of a gay-straight alliance group in 2011.

‘One of the things they did this year was a Think Before You Speak Week to get the students thinking before they say “that's so gay,” Unley High School principal Susan Cameron told Adelaide Now, adding that students had also been asked to sign a similar pledge.

Former Unley High student Indianna Wishart, who helped set up the gay-straight alliance at the school said the initiative had seen real changes in the culture of the school.

"Gay" became a slur that was unaccepted in classrooms and the schoolyard and teachers took an active role in policing its use,’ Wishart told Blaze magazine.

‘Previously it flew under the radar as a form of adjective that wasn’t treated very seriously. I think there has been a reduction in its use and I also think students are thinking more about what it means when they say it.’

Wear it Purple Day was established following the death of US gay teen Tyler Clementi in September of 2010 and is traditionally held on the first Friday of September in Australia.

Wear it Purple Day has been embraced by many Australian state governments and was this year given significant support by the NSW Police Force.