how can I purchase German Rail pass at Frankfurt airport / frankfurt railway station. can it be purchase in cash or only credit card acceptable ?
Credit cards are accepted. Be prepared to show your passport.
The bahn's airport ticket office is in Terminal 1, Area B, Level 0 (one level below street level), see the red DB on this downloadable pdf map. It is near an s-bahn entrance and several ticket machines. It may be easier to buy at the main train station.
Thanks for reply. Is it possible to buy German Rail Pass by cash payment ?
Of course you can. Cash is still used for a lot of transactions in Germany.