Certificates play a critical role in mobile applications. By exploiting certificates, mobile applications are capable of accessing the trading or other m-commerce services (mobile commerce) on mobile environments. WTLS (Wireless Transport Layer Security) [1], WPKI (Wireless Public-Key Infrastructure) [3], WIM (Wireless Identity Module) [5], and WMLScript Crypto Library [6] are defined in WAP [15]. Though the formats of certificates seem abundant, they are not compatible with the existing Internet X.509 certificates [7]. Therefore, we design and implement a WAP Certificate Converter Toolkit to provide the convenient interfaces. By using this toolkit, X.509 certificates can be converted into WAP compatible form, and then deployed in WAP-enabled mobile devices. The functions designed can let the Internet CA's (Certification Authority) dynamically and easily transform their issued certificates into WAP certificates. Besides, we consider some issues including mechanism enhancement and processing cost reducing. In brief, the toolkit can provide a userfriendly development environment to accelerate commerce application on mobile environments.