Francesco Plateroti lost a 13th century Chinese scroll "The Banquet of Immortals on the Terrace of Jade" by Wang Zhenpeng on the Paris-Geneva TGV mid-November.
Plateroti went to Paris to present the Chinese scroll for an art foundation exhibition, but on his way back to Bellegarde sur Valserine (near Geneva), he left the precious artwork on his seat.
"I was devastated when I realised I didn't have it with me", said Plateroti who offered a reward to anyone who returns it.
He alerted the staff of the TGV, but nothing was found on arrival in Geneva.
The unlucky Plateroti appealed for witnesses who might also have been on 8:11 pm TGV 9789 from Paris to Geneva on 21st November.
"I call the Swiss department of the lost property three times a day", said Plateroti.
However, the painting cannot be legally sold as Plateroti is the only one who has its certificate of authenticity, neither can it be exhibited.