Port Kembla artist Evan Salmon's work has been added to the permanent collection at Parliament House in Sydney, after he won the prestigious NSW Parliament Plein Air Painting Prize and $20,000.

The piece, Views of Port Kembla, was painted over four panels of marine plywood, and features different aspects of the historic coal export facility.

Plein air (French for "in the open air") painting was first popularised by artists including Monet and Renoir before being embraced by Australian artists including Tom Roberts and Arthur Streeton.

"It's fantastic to receive such recognition for my work as a painter and a great incentive to keep going with plein air painting," Mr Salmon said.

"I'm filled with excitement and nervousness as I contemplate starting a painting. Once I find my subject I've only a short time to record the light before it inevitably changes."

Senior curator at the Mosman Gallery and competition judge Katrina Cashman said the competition had drawn many exceptional artists.

Making a plein air painting was a very difficult thing, she said. "What you're essentially asking that painter to do is in a very small fleeting moment of time you're capturing an image or likeness of a particular image, and something that shows a great understanding of the subject."

Six Illawarra artists were finalists in this year's award, including Tony Hull, Kate Broadfoot, Richard Claremont, Ashley Frost and Paul Ryan.

All 42 pieces of work will be on display in the fountain court of the NSW Parliament until Friday, July 31. Entry is free, it is open Monday to Friday from 8am to 5pm.