The 7-inch ViewPad features Wi-Fi and 3G connectivity, along with GPS, a USB port, support for microSD cards and a camera on both the back and the front of the tablet.
ViewSonic is also launching a 10-inch version, which will be able to boot both Android and Windows and feature an Intel processor
The company also said it would use the show to unveil a range of 3D products including a lightweight handheld digital camcorder that captures and displays content in 3D, as well as a 3D handheld TV and photo frame.
"ViewSonic are focused on providing a full 3D experience, allowing our users to not only view 3D in the best possible way, but now create their own affordable content," said James Coulson, marketing manager, ViewSonic Europe.
"We believe by making 3D simple to use, whilst providing a complete solution, we can introduce 3D technology to consumers who were hesitant about new technology or concerned about the cost."
ViewSonic said further details about all of the products would be revealed at the show.
Toshiba is also thought to be working on a tablet PC to rival Apple's iPad.
Website Notebook Italia claims to have got hold of leaked image of the devices, which is expected to be called the Toshiba SmartPad.
The 10-inch device is expected to be powered by the Nvidia Tegra 2 platform and will run Google's Android operating system.
From the pictures, the sleek black tablet appears to features a silver trim and four touch-sensitive buttons. According to rumours, the SmartPad will also come with a webcam, HDMI port and USB connector.
The device is expected to be launched at the IFA consumer electronics show which will take place in Berlin next month.