Latex stage epoxidation of natural rubber (NR) with in-situ formed performic acid has been studied and the effects of speed of agitation, mode of addition of reagents, type of secondary acid and neutralization techniques on product quality are reported. Increase in agitation speed resulted in a more desirable product distribution but too high a speed created other problems like frothing and microcoagulation of rubber. The mode of addition of reagents, whether simultaneous or dropwise, was found to affect the product distribution. The extent of hydrofuranization was lower when acid of lower strength was used. Neutralization of the reaction mixture before coagulation gave products with improved aging properties.