Impersonal, non-face-to-face contact and text-based interfaces, in the e-Learning segment, present major problems that are encountered by learners, since they are out on vital personal interactions and useful feedback messages, as well as on real-time information about their learning performance. This research programme suggests a multimodal, combined with an edutainment approach, which is expected to improve the communications between users and e-Learning systems. This thesis empirically investigates users’ effectiveness; efficiency and satisfaction, in order to determine the influence of edutainment, (e.g. amusing speech and facial expressions), combined with multimodal metaphors, (e.g. speech, earcon, avatar, etc.), within e-Learning environments. Besides text, speech, visual, and earcon modalities, avatars are incorporated to offer a visual and listening realm, in online learning. The methodology used for this research project comprises a literature review, as well as three experimental platforms. The initial experiment serves as a first step towards investigating the feasibility of completing all the tasks and objectives in the research project, outlined above. The remaining two experiments explore, further, the role of edutainment in enhancing e-Learning user interfaces. The overall challenge is to enhance user-interface usability; to improve the presentation of learning, in e-Learning systems; to improve user enjoyment; to enhance interactivity and learning performance; and, also, to contribute in developing guidelines for multimodal involvement, in the context of edutainment. The results of the experiments presented in this thesis show an improvement in user enjoyment, through satisfaction measurements. In the first experiment, the enjoyment level increased by 11%, in the Edutainment (E) platform, compared to the Non-edutainment (NE) interface. In the second experiment, the Game-Based Learning (GBL) interface obtained 14% greater enhancement than the Virtual Class (VC) interface and 20.85% more than the Storytelling interface; whereas, the percentage obtained by the game incorporated with avatars increased by an extra 3%, compared with the other platforms, in the third experiment. In addition, improvement in both user performance and learning retention were detected through effective and efficiency measurements. In the first experiment, there was no significant difference between mean values of time, for both conditions (E) & (NE) which were not found to be significant, when tested using T-test. In the second experiment, the time spent in condition (GBL) was higher by 7-10 seconds, than in the other conditions. In the third experiment, the mean values of the time taken by the users, in all conditions, were comparable, with an average of 22.8%. With regards to effectiveness, the findings of the first experiment showed, generally, that the mean correct answer for condition (E) was higher by 20%, than the mean for condition (NE). Users in condition (GBL) performed better than the users in the other conditions, in the second experiment. The percentage of correct answers, in the second experiment, was higher by 20% and by 34.7%, in condition (GBL), than in the (VC) and (ST), respectively. Finally, a set of empirically derived guidelines was produced for the design of usable multimodal e-Learning and edutainment interfaces.