From a humble start of a handful of music enthusiasts to over a hundred members with different nationalities, the HKOS has been guided by generations of great musicians has become the most active choir with the longest history and the largest membership in Hong Kong. It usually presents five concerts per year with a total of more than three hundred concerts presented in the last fifty years. Its repertoire covers oratorios and major choral works by classical and contemporary composers. They include the masterpieces of Bach, Handel, Haydn, Mozart, Mendelssohn and Chinese composers Xian Xinghai and Huang Zi, etc. Many of these works were debut in Hong Kong.

HKOS takes its name from its favourite genre of repertoire, the oratorio, which refers to extended choral works with religious or mythological stories. In recent years, HKOS has commissioned composers Chan Wing-wah, Victor Chan and Huang An-lun to write music. From 1996, HKOS has also produced four CD recordings distributed worldwide.

The first conductor of the choir was Mr Frank Huang who was then succeeded by Dr Wong Wing Hee serving as Principal Conductor and Conductor Emeritus for many years before retiring. The present Music Director, Prof. Chan Wing-wah took over the baton after a few successful collaborations with HKOS since 1995. The current Honorary Patron is Mrs Selina Tsang, wife of Donald Tsang, Chief Executive of HKSARG.

The choir has performed under the batons of many famous conductors including Yan Liang-kun, Yan Hui-chang, Chen Zuo-huang, Shao En, Yu Feng, Chen Tscheng-hsiung, Zhang Yi, Cao Ding, Andrew Cheung, Jimmy Chan, Raymond Fu, Allison So, Carmen Koon, David Wilcox, Veiga Jardim, etc. The Central Ballet Symphony Orchestra of Beijing, Shenzhen Symphony Orchestra, Macao Orchestra, Taiwan Symphony Orchestra, Hong Kong Sinfonietta, Hong Kong Philharmonic Orchestra and The Hong Kong Chinese Orchestra had all collaborated with the HKOS. HKOS has also gone on overseas tours to Canada, Israel, the Philippines, Korea, Taiwan, Singapore as well as many major cities in Mainland China.

HKOS members are keen music lovers and enjoy singing. Its planning and execution are managed by the committee members on a non-remunerative basis elected by all members during the annual general meeting. The Music Director and Honorary President are ex-officio members of the Executive Committee. The concerts are supported by several generous patrons. HKOS has been contributing to Hong Kong through singing such as the continuous collaboration for 17 years in the form of charity concerts with the Hong Kong Japanese Club Choir.