Edward McKenzie-Green, 34, is said to have plundered £62,857.58 while working for the aid organisation between February and December 2011. He is also accused of stealing a laptop from Oxfam offices on December 1, 2011.
His father Edward Green, 61, of Cumbernauld, is accused of laundering £35,571.75 of the proceeds of the fraud. Both have already entered not guilty pleas.
McKenzie-Green appeared in the dock at the Old Bailey for a plea and case management hearing. His father was excused from attending.