Oracle Says yes:
1) Can I restore or duplicate my previous version database using a later version of Oracle?
For example, is it possible to restore a 9i backup while using the 10g executables?
It is possible to use the 10.2 RMAN executable to restore a 9.2 database even if the restored datafiles will be stored in ASM. RMAN is configured so that a higher release is able to restore a lower release, but it is strongly suggested you use only the same version. In this scenario for a restore (not RMAN duplicate) you will be using the restored 9.2 database against 10.2 binaries. If you intend to run the restored 9.2 database against the 10.2 binary files you need to run the upgrade steps to make the restored 9.2 database a 10.2 database, but understand that the pre-upgrade checklist which you may have submitted against the source 9.2 database does NOT apply to this restored 9.2 database.
Once the restore / recovery is completed you will need to open the database with a combination of the resetlogs option and the upgrade option. For example:
SQL> alter database open resetlogs upgrade;
After the database is opened in this fashion run the upgrade steps for the higher version. If you have any problems with any part of this process please open a service request. If you are restoring using backups created by an earlier release, some time after you have upgraded the database, then media recovery will re-play the changes that were made during the upgrade, and you do not need to run the upgrade scripts again.