There were almost 2,000 more professional jobs vacancies open last month compared to a year ago - with vacancies increasing to 10,120.
Compared to July, 4pc more jobs were available in August.
In some sectors firms are struggling to fill jobs because of the gap between salaries on offer and the pay expectations of some in-demand specialists - that gap is especially true in engineering. However, the numbers of professionals seeking jobs has also increased since August 2013, by 9pc to 8,930.
That's according to the latest Monthly Employment Monitor published by recruitment company Morgan McKinley. The monitor tracks the number of professional job vacancies across Ireland.
August is traditionally regarded as a quieter month for recruitment, making the latest increase a surprise.
The rise in the number of jobs available between July and August is "a real sign of improvement", according to Morgan McKinley's Karen O'Flaherty.
"As July was itself a strong month for recruitment, the unprecedented increase in job vacancies for August is proof of a robust and strengthening professional jobs market," she said.
"Further evidence of this is seen in the fact that the number of vacancies is almost a fifth higher in August 2014 compared to the previous year." The fact that the jobs being created are permanent roles - rather than contract position - and are in new divisions of expanding companies is particularly positive, Ms O'Flaherty said.
More vacancies however creates more scope for job mobility, especially in the busiest sectors, creating challenges for employers.
As staff retention has become harder for companies, the past six months have seen improving packages for finance and accounting staff, as well as for those with niche technology skills, according to Morgan McKinley.
Technology workers with mobile and internet skills are among the most in-demand candidates.
Accounting and professional services company Deloitte has announced that it's seeking to recruit 300 new staff - 200 graduates trainees and 100 experienced hires.
The jobs are at its offices in Dublin, Cork and Limerick.
The graduate jobs are in areas including audit, internal audit, tax, corporate finance, consulting and technology.
Graduate recruits will start work at Deloitte in autumn 2015 or 2016.
The firm is looking to recruit experienced staff across the same areas as well as in cyber security and forensics. Deloitte currently employs 1,350 staff in Ireland.