The new shop is scheduled to open at the top of City Road at Manor Top later this year.
It will sell a full range of second hand fashions, bric-a-brac, books, CDs, DVDs and housewares and will also stock furniture and electrical items.
But to keep the shop open six days every week it's estimated there will be a need for the support of up to 40 volunteers.
“This is a great way of gaining some retail experience and making a real contribution to Sheffield’s only hospice,” said St Luke’s Head of Retail Paul Summerland.
“Our volunteers receive in depth training in areas such as sorting, tagging, pricing, steaming and merchandising as well as learning about effective customer service.
“It’s a fun and lively thing to be involved in a new shop opening and we have an amazing management team who want to meet like-minded individuals who want to make a difference.
“Just one hour every week can help make an enormous contribution to the lives of St Luke’s patients and their families.”
If you'd like to volunteer, or would like more information on volunteering please email Joy Wigfield or call 0114 235 7542.