A skullcap worn by Pope Francis is expected to make ?�19,550-25,420 ($28,009-36,419).
The lot is selling on online auction site Catawiki, with bidding due to close on April 24.
It's become a Papal tradition in recent years to swap a skullcap (or zucchetto) with a worshipper.
The consignor, an Italian TV host, explains: "It was June 4, 2014 when, during the general audience in St Peter's square in Rome, my eyes crossed that of Francis.
"After exchanging glances, a gesture: I exchanged my headdress with that of the Holy Father. A simple gesture, but equivalent to the Christian religion to have received a pardon.
"The magnetic effect of the object owned and worn by the Pope was immediate, so much so that the skullcap still bears today a slight sign of lipstick from a follower, who wanted to kneel and kiss the Holy Father's headgear."
Items owned by the Pope are rarely sold. After his death it becomes a relic, which is likely to further encourage bids.
Auctioneer Fredeik James comments: "It is extremely rare that a religious symbol of this magnitude goes up for auction.
"This auction is a unique opportunity for museums, collectors and devout Catholics to acquire 'a relic in the making' and also to help others by donating money to Save a Child's Heart.
"Given the Pope's following, we expect to see an influx of bids from across the globe."
Part of the proceeds from the sale will go to benefit Israeli charity Save a Child's Heart.
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