Yes, but you may have less options and pay more:
Visit a Eurail Aid Office if you need help with your Eurail Pass, or
if you arrive in Europe without having purchased a pass. Eurail Aid
Offices are almost always located within large train stations; consult
the list at //www.eurail.com/eurail-aid-offices to find one in your
country of origin or destination.
If you cannot find a Eurail Aid
Office in your country, Eurail recommends asking for help at the
international ticket window in a large train station.
The only Eurail
passes available for purchase in Europe are: single-country passes to
Romania, Portugal, Norway, Italy, Ireland, Hungary, Greece and
Croatia; multiple-country passes for Hungary-Romania, Greece-Italy,
Austria-Hungary, Croatia-Slovenia-Hungary or Austria-Croatia-Slovenia;
Eurail Select Passes, and the Eurail Global Pass.
Eurail.com has a list with offices where you can buy the pass but they say:
Online Eurail.Com prices are on average 20% lower than the prices
charged at European train stations. Not all Eurail passes are for sale