On May 26, 1967, a public debate was held titled "Rational Emotive Behavior Therapy vs. Objectivist Psychology." Ellis, of course, represented REBT, while Nathaniel Branden (psychologist and Ayn Rand follower at the time), represented the Objectivist side.
More than 1100 people attended the debate, most of whom were followers of Objectivism. Ellis claims to have shown many of the irrationalities of Objectivist thought all while they loudly booed him. Ayn Rand sat in the audience and became extremely upset when Ellis made comments on the characters in her novels.
As a result of this debate Ellis published Is Objectivism a Religion? In it he posits his opinions on Objectivism.
I have posted a letter here from Ellis to Branden. This letter is Ellis’ response to a letter Branden sent him, condemning his behavior at the REBT vs. Objectivism debate.