Depends on the client. A major hole is Telepathy, which lacks end to end encryption support, so all mobile clients based on that (Sailfish one, Plasma Active one and etc.) are lacking it. Jitsi (which is in Java and WIP in alpha stage for Android) supports OTR and ZRTP. There are clients like Xabber which support just OTR on Android (none of them support Jingle and ZRTP). Not sure about the situation on other mobile OSes.