Chesapeake Energy filed suit on Tuesday accusing its founder and former chief executive of seizing proprietary oilfield prospect data before he stepped down in 2013.
Chesapeake alleged that Aubrey McClendon "stole" a trove of "highly sensitive" maps and prospect data before he was pushed out of the company in April 2013.
McClendon allegedly emailed dozens of emails to himself containing the data and had Chesapeake staff print out other sensitive materials.
McClendon later used the data to buy land in the Utica Shale region in Ohio for his new company, American Energy Partners (AELP), to explore for potential hydrocarbon deposits, the complaint said.
McClendon affiliates "used and disclosed Chesapeake's trade secrets," said the complaint, filed in an Oklahoma court.
"In so doing, they have misappropriated Chesapeake's trade secrets."
Chesapeake asked the court to award it unspecified royalties and damages.
McClendon called the complaint "baseless" and said he planned his own legal action against the company for violating the agreement the two parties struck ahead of his departure.
In a statement American Energy said that, based on his separation agreement with Chesapeake, McClendon was promised access to extensive information on 16,000 oil and gas wells he co-owns with Chesapeake and on related leaseholds and future wells.
That deal "gave Mr. McClendon the right to own and use this information for his own purposes," the statement said.
"Now it appears that Chesapeake wishes it had not agreed to the deal it made with Mr. McClendon and has sued to break those promises."
"However, a deal is a deal and Mr. McClendon and AELP will be vindicated in this dispute, and Mr. McClendon's contractual rights to keep and use the information he received in the deal will be affirmed."
A leader in the American shale boom that has transformed global energy markets, Chesapeake pushed out McClendon two years ago amid investor criticism over the company's aggressive spending and complex financial dealmaking between Chesapeake's corporate accounts and McClendon's personal fortune.