Which particular physiological processes and anatomical units are sufficient for subjective experience? While modern science of consciousness originated from the search for its neural correlates, these have not yet been conclusively determined, due to the complexity of the matter and competing theoretical worldviews. Most of the studies have been conducted on perceptual visual awareness. In this thesis, I investigate the neural correlates of consciousness in auditory, visual and multisensory contexts. I also discuss the theoretical and methodological ground of this research program and introduce four empirical studies followed by a systematized review. The research aims to identify the most prominent, robust and universal electrophysiological correlate of perceptual consciousness, broadening current understanding of the subject. Study I examined consciousness in visual, auditory, and visuo-auditory bimodal conditions, revealing both modality-specific and modality-general neural activity. In particular, early electrophysiological responses labelled visual and auditory awareness negativities indexed consciousness, whereas the late positivity did not. Study II examined whether auditory correlates of consciousness are influenced by feature-based attention and response requirements, revealing a similar component as in Study I and validating this independence. Study III examined whether transition from unawareness to awareness of sounds is gradual or abrupt, revealing that this depends on the level of stimulus processing, whereas the neural correlate of consciousness remained unaffected. Study IV investigated if auditory awareness negativity is present in simple auditory hallucinations as it does in perception, further validating it as the most prominent and robust electrophysiological correlate of auditory consciousness. In conclusion, Study V revised recent findings in the visual domain and determined that visual awareness negativity is the most prominent correlate in vision. Present findings have consequences for different ongoing debates and contemporary theories of consciousness, offering backing for some of them while offering challenges for others.