The company had guided revenue of A$300 million, with the actual figure of $324 million 14% higher than the December 2017 half.
Two thirds of the company's revenue came from the gold sector.
EBITDA was down 27% to $27.6 million, while EBIT dropped 28% to $10.1 million.
Net profit after tax fell 33% to $8.1 million, in line with the company's revised guidance of $7-9 million.
MACA declared an interim dividend of 2c per share, fully franked, down from 3.5c.
The company had "modest" net debt of $6.5 million at December 31 due to the significant capital investment made during the half.
Cash at bank was $71.6 million.
The company's order book as of February 19 stood at $2.2 billion, which includes $530 million of work from Echo Resources and Emerald Resources, yet to be finalised.
MACA said despite a disappointing first half, it had a positive outlook for the second half due to its increased work in hand and promising project pipeline.
Full-year revenue is expected to be $640 million, up from the previous estimate of $620 million.
"The second half financial performance is expected to be stronger than that achieved in the first half as a result of improved margins," MACA said.
MACA shares dropped 1.5% to 97c yesterday, capitalising the company at just under $260 million.
Canaccord Genuity maintained a buy rating for MACA and lifted its price target from $1.23 to $1.28.