Since 1998, Calcium Magnesium Acetate (CMA) has been trailed by Transit New Zealand in the Coastal Otago region of New Zealand as an anti-icing and de-icing agent for state highways. During the trials, there were instances where vehicles had lost control on a road surface that had been treated with CMA to prevent ice formation. This raised the issue as to whether or not skid resistance was reduced by the presence of CMA. The time of day the CMA was applied also appeared to be an important consideration, application in late afternoon resulting in a greater likelihood of a loss of control incident occurring than application in the early hours of the morning, close to ice formation. Unlike countries where CMA has been successfully introduced for winter road maintenance, New Zealand has far less severe winter temperatures, higher relative humidity, and more highly textured road surfaces with 90 per cent of the state highway network being coarse chip seal. Therefore, a controlled study, which utilized a climate chamber, was conducted to establish whether or not the addition of CMA to representative New Zealand road surfaces would initiate a temporary reduction in skid resistance and to quantify the magnitude and duration of this reduction under different climatic conditions experienced during the course of a typical winter's day. It was found that a CMA solution reduces the skid resistance of a dry road surface more than water alone under identical climatic conditions, the additional reduction in the coefficient of friction being of the order of 0.15 to 0.3. In addition, a sensitivity to humidity level was observed, this being especially noticeable when the CMA solution had partially dried, confirming Canadian findings. CMA also encourages the road to stay moist and slippery much longer than occurs for water alone. When dry, CMA on a road surface had no effect on the skid resistance, but was reactivated with an attendant reduction in skid resistance by dew-like quantities of water. This reduction lies midway between the wet only condition and the CMA wet value. However, compared with a black ice situation, CMA results in a significant improvement in the road's coefficient of friction of between 0.1 and 0.25 depending on surface type and so its continued use in New Zealand for winter road maintenance is advocated but with modified application procedures to better manage any potential temporary hazards for motorists.