Brown, 56, was scheduled to be put to death at 12:01 a.m.
Wednesday for the 1980 rape and murder of a 15-year-old girl in Riverside.
The governor blocked the execution for 45 hours, according to the California Department of Corrections and Rehabilitation. Brown’s execution is now scheduled for 9 p.m. Thursday.
Earlier today, a Marin County Superior Court judge declined to grant a stay of execution.
Judge Verna Adams said Brown’s lawyers had not proved he would suffer extreme pain if executed according to the state’s lethal injection protocol.
In the case before Adams, Brown contended that the state’s adoption of a recently revised lethal injection protocol violated a California law on procedures for new regulations.
Sara Eisenberg, a lawyer for another condemned inmate, Mitchell Sims, said Brown and Sims would appeal immediately to the state Court of Appeal in San Francisco.
The Marin County case is one of two in which Brown is seeking to block the execution.
The other case is a federal court challenge based on the claim that the state’s lethal injection procedure is unconstitutional cruel and unusual punishment because it has the potential to cause extreme pain.
A federal trial judge in San Jose refused to stay the execution in that case, but Brown’s lawyers have appealed that ruling to the 9th U.S. Circuit Court of Appeals in San Francisco.
If Brown were put to death, it would be California’s first execution since January 2006.