Objectives: To examine the extent and characteristics of food and beverage (F&B) promotion in Hong Kong mass transit railway (MTR) stations in districts with different socioeconomic statuses (SES) and school density. Design: All advertisements located in the eight selected MTR stations were recorded by photographs or videos, and classified into F&B and non-F&B. The percentage of F&B advertisements and unhealthy F&B being promoted, and common persuasive marketing strategies used in F&B advertisements were compared between low v. high SES districts and school zones v. non-school zones. Setting: MTR stations in Hong Kong. Participants: Not applicable. Results: Of the 8064 advertisements documented, 861 (10·7 %) were F&B advertisements, promoting 1860 F&B items. More than half of the these were unhealthy foods. Stations in high SES districts or school zones tend to advertise more unhealthy items (high v. low SES: 55·8 v. 50·8 %, P = 0·049; school v. non-school: 60·8 v. 49·3 %, P < 0·001). More than one-third of the F&B advertisements recorded did not utilise any of those persuasive marketing techniques that were examined, and using models (13·9 %) or providing discounts (8·8 %) were the two most frequently used non-festival-related persuasive marketing strategies. Conclusions: Unhealthy F&B advertising in MTR stations is prevalent regardless of SES and school density, and persuasive marketing strategies were infrequently used. These suggest that a ban on unhealthy F&B advertising around schools or the use of persuasive marketing strategies alone would be ineffective in Hong Kong. To align with the recommendation from WHO, a universal ban of junk food advertising should be enacted.