The transition towards a green energy production system relies on the development of proper energy storage devices that could meet the requirements in terms of durability, costs and performance, complying with the sustainability criteria. In this regard, Zn-based devices are emerging as a promising alternative due to the availability, low-cost and recyclability of this material. Furthermore, being stable in aqueous media they also bring about enormous improvements regarding safety issues [1]. Both Zn-air and Zn-ion batteries have therefore been the subject of a growing number of investigations recently. In this context, Prussian blue (PB) and its analogues stand out as a Zn⁺² intercalation cathode materials not only for their high working voltage, low cost, and ease of synthesis but also because they are non-toxic [2,3]. However, their low electronic conductivity limits the rate capability and cycling stability of PB cathodes. The growth of PB crystals directly on carbon materials to obtain composite materials with high electronic conductivity, which retains the electrochemical properties of PB has been already proven as an approach to enhance the performance of Na-ion [4]. Based on this, in the present study, the potential of PB grown in-situ on Ketjen Black carbon (PB@KB) as cathode materials for Zn²⁺ intercalation has been evaluated. Two synthesis methods were used to obtain PB@KB: a standard thermal synthesis using mechanic agitation and an ultrasound-assisted methodology. The effect of reaction parameters (temperature, KB initial content and time) was evaluated for the second method. The main objective of this work was to correlate the materials properties, i.e. PB crystallinity and size, KB content, among others, with the electrochemical response towards Zn²⁺ insertion to optimize Zn-ion devices. Materials have been characterized to determine the size distribution and crystallinity, and electrochemical characterization in 2 M ZnSO₄ solution was done using both three-electrode configuration (Swagelok cell) and coin cells by CV and GCPL techniques, using Zn foil as counter electrode. The performance as cathode for Zn-ion batteries was assessed by estimation of the capacity, energy density and both coulombic and energy efficiency. The preliminary results show that the ultrasonic irradiation can provide a similar material, in terms of PB content and reaction yield, after just 6 hours (compared to the 20 h needed for mechanical agitation). In addition to this the average PB size is significantly decreased. Results also indicate that temperature is crucial to achieve good reaction yield and that KB provides nucleation sites based on its impact on the PB size. The synthesized materials can intercalate Zn²⁺ efficiently leading to 120 mAh/g capacity at 100 mA/g in Zn-ion full cell configurations.