Miriam Webb, who founded Worthing firm Electronic Temperature Instruments with husband Peter in 1983, presented the cheque to treasurer David Baldwin.
She said the company wanted to contribute towards the disabled and family toilet society members are constructing at their clubhouse at Field Place.
The society said it heard late last year that ETI was going to donate a considerable sum to its disabled toilet building fund and members were grateful.
The official presentation took place on Wednesday, April 11, and members felt fortunate when they were told the sum had doubled to £1,000.
Club members regularly meet on Wednesday mornings to carry out essential maintenance and building work.