This thesis explores the implementation of kindness in the public sector through the adaptation of the Service Design process. Traditionally, public service delivery has been predominantly focused on economic efficiency and effectiveness, often neglecting the human component of the individuals involved. This thesis aims to expand the rational approach by incorporating emotional states to better address citizen needs. By conducting an extensive literature review, kindness emerges as a promising concept for transforming public systems and processes towards a more citizen-centred approach, particularly in enhancing human-to-human interactions within these services. Drawing upon Research through Design and the IDEO 3I methodology, this research develops tools for Service Designers to analyse kindness in public services, explore opportunities for its integration, and create concrete approaches for fostering relational services. Through qualitative research encompassing surveys and expert interviews, kindness is explored interdisciplinarily and in depth to establish a strong foundation for building the pillars of kindness in public services. By employing ideation workshops and testing with Service Designers, a toolkit is developed that aims to integrate the highly versatile and subjective concept of kindness into their practices. The thesis presents three distinct tools that broaden the scope of Service Design, shifting the focus from the design of service functions to the manner in which they are performed through the lens of kindness. The use of these tools within Service Design processes ultimately aims to enhance the connection between service users and providers, fostering a solid foundation of trust between citizens and government. This endeavor strives to initiate the transition from a rational to a relational public service approach, with Service Design acting as a catalyst for effective and user-centered public service development. By intertwining kindness and Service Design, this work serves as a initial effort, stimulating broader discussions and inspiring future research in these areas.