17 September 2018

Mosman Oil and Gas Limited

("Mosman" or the "Company")

Hydrocarbon Production and Sales at Stanley-1

Mosman Oil and Gas Limited (AIM: MSMN) the oil exploration, development and production company, is pleased to provide the following update to operations at Stanley-1 (Mosman 16.5% working interest).

Mosman has been advised by its partner Baja Oil and Gas LLC ('Baja") the following information:

"The Stanley-1 well, drilled in late July 2018, is flowing gas and liquid hydrocarbons (oil/condensate) to sales. Production is currently, and temporarily, constrained by the existing surface equipment limitations. The well is currently flowing hydrocarbons to surface at an equipment constrained rate of 67 barrels of oil equivalent per day ("boepd"), approximately 12% hydrocarbon liquids and with no water production. Once the existing surface facilities are upgraded to handle increased production rates, Baja expects to increase average daily production from the well-bore to approximately 230 boepd. Production from the well initially will be high yield natural gas and liquid hydrocarbons, and Baja expects that the production mix will change from natural gas with substantial liquid hydrocarbons to oil with substantial associated natural gas. Surface equipment upgrades will be undertaken over the next several weeks.

John W Barr, Chairman, said: "Mosman is extremely pleased with the short time it has taken from spudding the well to sales. We anticipate that surface equipment upgrades will increase production. Planning has now commenced for a follow up well, Stanley 2."

Competent Person's Statement

The information contained in this announcement has been reviewed and approved by Andy Carroll, Technical Director for Mosman, who has over 35 years of relevant experience in the oil industry. Mr. Carroll is a member of the Society of Petroleum Engineers.

Market Abuse Regulation (MAR) Disclosure

Certain information contained in this announcement would have been deemed inside information for the purposes of Article 7 of Regulation (EU) No 596/2014 until the release of this announcement.

Enquiries:

Updates on the Company's activities are regularly posted on its website www.mosmanoilandgas.com