The hunt is on to find the relatives of people pictured in three black-and-white portraits discovered lost at the Queensland Museum.

The photos depicting a man and two women, impeccably dressed with beautiful hairstyles, were found on the floor following the launch of a book about World War I tank Mephisto last July.

The portraits were taken at Irving Studios in Rockhampton. ( ABC Radio Brisbane: Jessica Hinchliffe )

"One of our visitor officers picked them up and they had obviously been dropped out of someone's handbag or folder," museum spokeswoman Kylie Hay said.

"The photos have been living in the lost and found for the past 12 months and no-one has collected them — they are too important to not find the owners."

Museum staff believe the people depicted in the images were family members in their late twenties.

"From our historical research, we believe the photos are from the 1920s and shot at the Irving Studios in Rockhampton," Ms Hay said.

"Those studios no longer exist, so we couldn't go to them and find a source.

"They are definitely treasured memories and the people are very stylish and beautifully dressed."

Notes to grandfather

An inscription on the back of one photo reads: "To grandfather with love from Pat."

Another photo, this one of "Evie", has a similar inscription.

The photos were gifts from Pat and Evie to their grandfather. ( ABC Radio Brisbane: Jessica Hinchliffe )

"Unfortunately, we don't know the name of the man in the photos," Ms Hay said.

Along with the written notes, one of the photos has artwork on it.

"It seems a child has taken a red pen to the back of one of the photos and has done a little arts and craft."

Looking for Evie and Pat's grandchildren

The photos are in near-perfect condition, leading the museum to believe they were intended to be shown or given to someone.

"They aren't faded or bent ... there's only a little fraying at the edge of one of the photos and there's no creases at all," Ms Hay said.

"Plus, with their hair — you just don't see hair like that anymore; no-one has the time to do hair like that."

The lost and found cupboard at the museum holds many items. ( ABC Radio Brisbane: Jessica Hinchliffe )

Ms Hay said she hoped that relatives of Evie or Pat come forward.

"It breaks our heart that [the photos] are still here with us, as we really want to reunite them with their owner," she said.

"We really want to see the photos returned to their owners — they may be the grandchildren of the people in the photos or a family member of Pat or Evie, and we really want to hear from them."