The AIM-listed company announced on 10 November last year that it had seen a significant reduction in its revenues.
Since the announcement, Expomedia has "vigorously explored options to address the company's working capital requirement".
The board said it has been in discussions with a number of parties, including potential equity investors, existing shareholders, the firm's bankers and key creditors.
"Until recently the directors were hopeful that funding would be secured," said a company statement. "The company has been unable to secure the required funding and it is with regret that the directors have decided today that the company should be put into administration."
Mash Media is believed to be negotiating a buy-out of its titles.
Expomedia Group works across exhibitions, conferences, venue management and publishing. It was floated on the AIM, the London Stock Exchange's junior market, in December 2001.