These days mobile application development involves multiple OS platforms like Android, iOS, Windows, Symbian, Java Mobile and the Moblin platform and a wide range of device technologies. Developed mobile applications should be delivered a consistently meaningful user experience across different devices and work successfully on various OS platforms. This may look easy on paper, but it is in fact greatly multifaceted, while putting into practice, because of a variety of aspects like highly fragmented mobile technology scenario, quickly evolving standards, constraints imposed by the mobile device itself (screen size, input methods, display capabilities, memory etc.). MoSync is a free and an open source Software Development Kit (SDK) for mobile applications. MoSync can build application packages for hundreds of different mobile devices on a wide range of mobile operating systems. This paper presents the design and implementations on not only economical but flexible and secure mobile phone based device control system using MoSync framework and eight bit microcontroller in an ad-hoc network environment. The devices are connected to the on/off relay via microcontroller ports and controlled through mobile phone. The communication between the mobile phone and the device control system is through Bluetooth wireless technology. This system is designed to be economical and modifying eight appliances to be controlled with minimum efforts.