Phil Brown, managing director of Youmanage, claims employers could be forced to pay out huge sums of money for not following the codes properly.
He said: "Tribunals now have the power to increase payouts by up to 25% if they find an employer has ‘unreasonably' failed to follow the code.
"In a sex or race discrimination case where payouts are unlimited, an extra 25% could prove to be very expensive indeed."
The codes came into practice in April in a bid to create more flexibility and resolve problems early before they escalate.
New Acas codes of practice 'could prove costly' to employers
The new Acas codes of practice, designed to simplify disciplinary and grievance procedures, could leave employers out of pocket, according to one industry expert.
