Matrai is known for her work on marine aerosols, especially those that contain sulfur. She has examined the production of sulfur compounds by coccolithophores, a type of phytoplankton. She has also examined the amount of organic sulfur inside phytoplankton cells and during phytoplankton blooms. Matrai has worked on the impact of declines in sea ice and how primary production is measured in the Arctic. In 2001 she went to the North Pole on an icebreaker where she studied aerosols produced by phytoplankton. She also does work on outreach and mentoring children to introduce them to science