Walkability is seen as an important concept for sustainable urban development and urban mobility. In urban context, the improvement of walkable areas promote personal, social, economic and environmental benefits to cities and their inhabitants. The main aim of this thesis was to make and evaluate a method to identify and assess pedestrian paths and networks in a central area of a city. The Pedestrian Network Assessment (PNA) Model has been developed as a methodological procedure to assess walkable conditions of streets and to evaluate the connectivity. So, this research describes a Geographic Information System based and integrated model to assess and identify streets as a pedestrian network, by using multi criteria and space syntax analysis. The multi criteria analysis covers a large number of walkable attributes (nine sub-criteria grouped in four main criteria) and a quantitative weight method was used to define the relative importance of the criteria following the experts’ vision. Space syntax was used to evaluate street connectivity. The PNA model was implemented in two cities with different urban morphologies, Porto (Portugal) and Qazvin (Iran). Findings show that in Porto there are few streets providing good conditions for pedestrians and that they are not connected as a network; in Qazvin, streets provide good conditions and they are better connected. In addition, the two case studies (Qazvin and Porto) have been presented to demonstrate the proposed methodology in order to be able to have a comprehensive evaluation of the PNA model under different urban morphologies. Moreover, the Angular Segment Analysis by Metric Distance (ASAMeD) was used to assess the impact of urban morphology of both cities on walking in urban area assessed and the results are compared to evaluate the PNA model comportment. The comparison between the PNA model and ASAMeD approach shows that the PNA model assesses the streets providing better information on walking conditions than ASAMeD. Thus, the Pedestrian Network Assessment Model is an innovative method that can be a useful tool to plan urban streets for pedestrians and to develop spatial relationships in street networks for walking. The PNA model has potential to provide planning guidelines for walkability improvement and to consolidate an urban pedestrian network in the central area of cities. Furthermore, the PNA model can potentially be replicated in other cities in terms of improving the walkability and to promote sustainable urban mobility.