Rita King, 81, who was believed to have dementia, was killed at De La Mer House in Walton-on-the-Naze, Essex on Monday, 28 December.
Her husband, Ronald King, of Cedar Close in the seaside town, appeared at Chelmsford Crown Court.
Mr King, who came into court on crutches, was remanded in custody and will face trial on 4 July.
During a brief hearing, Mr King spoke only to confirm his name and enter his plea.
He was told he could remain seated during the 10 minute hearing.
An 86-year-old man has pleaded not guilty to murdering his wife who was shot dead in a care home.