Mike Hayes, Action for Kids' chief executive, told Third Sector that he feared the names were too similar.
"We have spent considerable time consolidating our brand and acquired significant goodwill," Hayes said.
"Rebranding will only increase any misunderstanding and potentially have a detrimental effect on our work."
He said the charity was contacting the Charity Commission and its solicitors in an effort to protect its name.
NCH first trademarked the name NCH: Action for Children in 1994 - after Action for Kids was created, but four years before it became a charity.
It dropped the strapline six years later. Action for Kids claim this was because the similarity between the two caused so much confusion. NCH counters that there was no evidence for this.
A spokeswoman for NCH said: "We are confident of being able to reassure Action for Kids that our distinct brand and clear identity at the time of our formal launch will not impact on their position."
She added that NCH had written to Action for Kids before announcing the name change but received no response.