What kind of paper is paper money printed on?

It is cotton based paper. Well among other things. Banknote paper is impregnated with polyvinyl alcohol or gelatin to give it extra strength. The exact composition is actually secret. "80 to 90 grams per square meter cotton paper, sometimes mixed with linen, abaca, or other textile fibres." -Wiki Mulberry bark fibre is used in Japanese banknote paper today. In 1983, Costa Rica and Haiti issued the first Tyvek and the Isle of Man issued the first Bradvek polymer (or plastic) banknotes. Over the years, a number of materials other than paper have been used to print banknotes. This includes various textiles, including silk, and materials such as leather.  more