The injection of capital is also expected to support the group following its recent acquisition of interests in two producing oil properties in the United States.
It said the proceeds will be put towards the ongoing development of the US projects, the Strawn Oil Project in Texas and the Arkoma venture in Oklahoma. The expectation is that these assets can provide production growth and cash flow.
"The placing will provide funding to progress the growth in the operational side of our two recent US onshore production acquisitions,” said John Barr, Mosman executive chairman.
“Our growth strategy remains focused on identifying further opportunities like Strawn and Arkoma that provide operating cash flow and have additional development upside, in conjunction with adding value to our existing exploration permits."
Mosman is issuing 42.8mln new shares, priced at 1.4p each.
In late afternoon trading, Mosman shares were over 9.5%, or 0.15p lower at 1.42p, but still held just above the placing price.
-- Adds share price --