Open the actions palette
Click the "layer icon" left to the dustbin
give your action a clearly discernable name
then start recording:
don't use any shortcuts here: always use menus!!!)
example:
Image>Mode change Lab to RGB
File>Save As (was a mac Tiff) PSD
Then click the square button (stop recording)
NOW OPEN FILE AUTOMATE BATCH
your new action will alredy be there in the top part of the dialog. If not, just browse
If the source is a folder, then choose source>folder, and browse to it
Also choose your destination folder, and evt the names your files shoud get.
Then run batch and voil?.
This is an example. If you have questions, just post them, but in that case: please incluce specific data.