Continuing miniaturization of electronic devices necessarily requires assembly of several different objects or devices in a small space. Therefore, besides thin films growth, the possibility of fabricating wires and dots [1, 2] at the nanometre scale composed of metal silicides is of the top interest. This report is about the STM/STS investigation of cobalt silicidesâ€™ nanostructures created on Si(111)-(âˆš19 Ã- âˆš19) substrates via Co evaporation and post deposition annealing. This (âˆš19 Ã- âˆš19) reconstruction was induced by Ni doping. Less than 1ML of Co on surface was obtained. Surface reconstruction induced growth of agglomerates of clusters rather than an uniform layer. The post deposition annealing of a crystal sample (up to 670 K, 770 K, 870 K, 970 K, 1070 K and 1170 K) led to creation of silicidesâ€™ nanostructures. Measurements showed that coalescence of Co nanoislands begun around 970 K. Annealing above 1070 K led to alloying of a Co, Ni and Si. As a consequence the Si(111)-(7Ã-7) reconstruction occurred at the cost of Si(111)-(âˆš19 Ã- âˆš19).