There is an increasing amount of literature that relates the implication of the theta frequency band (4-8 Hz) in spatial memory processes. Moreover, this could be sexually dimorphic, with males and females exhibiting differential patterns during spatial demands, such as landmark encoding, or a differential strategic process, as shown in evoked related potentials (ERPs) studies. However, this has been little explored in complex, allocentric-based spatial memory tasks with frequency band analyses. Thus, this study explored electroencephalographic (EEG) activity in a sample of 40 participants, all of them undergraduate students of the University of Almería (20 males, 20 females, age range 18-28 years). Their spatial performance was addressed using an EEG-adapted version of the Almeria Spatial Memory Recognition Test (ASMRT-EEG), an allocentric recognition task in a complex environment. Behavioral results showed that males outperformed females in spatial accuracy. Moreover, theta power spectral density analyses identified higher theta power density in females compared to males, and a differential activation pattern between both groups during the three phases of the task (encoding, maintenance, retrieval) for frontal, parietal and occipital regions. In this regard, males generally showed higher theta power for the maintenance phase. These results outline the differential brain pattern activation between males and females, which could be related to brain asymmetry which, alongside previous evidences from ERP studies. Future studies should explore this theta involvement further, alongside its potential connection with other frequency bands, such as high gamma (60-100 Hz).