Allow me to quote Oracle Note #132904.1

"The original Export client is desupported for general use as of Oracle Database 11g. Oracle recommends that you use the new Data Pump Export and Import utilities in Oracle11g and above, except if you need to import files into Oracle11g that were created using the original Export utility (exp), or if you want to export files from Oracle11g that need to be imported using the original Import utility (imp), e.g. importing into an 9.2.0.8 target database."