The 76-year-old and fellow former Birmingham owner David Sullivan took over at Upton Park in January 2011. Gold, who needed hospital treatment for cholangitis and septicaemia in March 2011, was taken ill after West Ham's FA Cup third-round clash with Manchester United.
On Tuesday night his daughter Jacqueline posted on her Twitter account, @Jacqueline_Gold: "Have taken my father into hospital. I think he's learnt a very harsh lesson - not to go to football with bronchitis, now has pneumonia!"
She took to the social media network again on Wednesday afternoon, revealing her father will not be at West Ham's trip to Sunderland this weekend.
"Just to update you my dad had a good night but is still on strong medication for his condition," she said.
"He is still very poorly but in good hands and obviously won't be at the game on Saturday."