Profits rose to £22.1m, compared with £17.8m last time, but the group, which has been hard hit by the slowdown in the US, is predicting flat revenue at best for the full year.
The group would not say how many jobs would be lost but did confirm that the bulk of the redundancies, around 400, have already taken place. It is expected that another 300 jobs will go, with the US taking the worst of the cuts.
Cordiant, which is the world's ninth-largest marketing services group, employs around 10,000 worldwide.
Revenues for the six months were up 45.2% to £308.8m from £208.6m 12 months ago.
Cordiant shares were up 1.67% this morning at 154p, having closed 20% down on the week at 149p on Friday.
Analysts were particularly concerned about the group's North American operation, where there is a reliance on technology-based clients. Last year, it bought US marketing group Lighthouse Global Network and, at £315m, is believed to have overpaid at the top of the market.
Revenues there were up by 74.7% to £100.8m and while many of the group's core clients have continued to increase marketing expenditures, Cordiant said substantial declines in spending from technology clients have impacted underlying revenue growth in North America.
Cordiant owns the Bates advertising network, as well as number of specialist communications and PR firms.
In a statement, Cordiant said trading conditions are likely to remain difficult, with the slowdown in North America now affecting economic growth in Europe and Asia Pacific. The group said it sees little immediate prospect for growth and, consequently, underlying revenues are expected to be flat at best for the year as a whole.
The group expects to incur a charge of £10m in 2001, part of which will be to cover severance pay. In addition to this, Cordiant's management is pursuing a wider-ranging cost-reduction programme throughout the group.
Michael Bungey, chief executive of Cordiant, said, "Since this management team took control of the group three years ago, we have all but trebled both revenues and operating profits, and aim to have nearly doubled margins by 2004. The current severe downturn in our markets requires that we continue to closely manage our cost base."
He added, "The business climate may have changed; the quality and, hence, profit potential of the portfolio of companies that we have assembled has not. We are better positioned than many to take advantage swiftly of the upturn when it comes."