This work presents the implementation of a small, light and wireless electroencephalogram (EEG) and intracranial EEG (iEEG) acquisition system called "Wireless Neuro Boards" (WIRNEBOs), intended for electrophysiological recordings in small animal models. The system consists of two devices: a battery powered transmitter, in charge of the acquisition and transmission tasks, whose dimensions and weight are 58 mm by 38 mm by 10 mm and 25 g respectively, and a receiver which is connected to a host computer to store and process the acquired signals. The main characteristics of the WIRNEBOs include the use of 24 bits, 8 channels medical Analog Front End (AFE). The system was tested with a sample rate of 500 samples per second (SPS) and has power autonomy up to 8 hours and presents an electric noise of less than 1μV. The wireless radiofrequency (RF) link did not present any corruption or data loss in a range up to 5 meters. Modular design is novel; allowing the implementation of new versions with higher number of channels and improvements in sample rate, autonomy, range of the communications, among others.