Proschwitz back at Paderborn
The 28-year-old German will return to his homeland on a free transfer when his Bees contract expires on Tuesday.
Proschwitz scored 17 goals in 33 appearances for Paderborn in 2011/12, form which earned him a move to Hull the following summer.
He joined Brentford in August 2014 and made 20 appearances, scoring just twice, and also spent nine games on loan with Coventry.