Abstract: We report the synthesis and optical properties of organic porphyrin nanoparticles with narrow size distribution and well dispersibility. Nanoparticles were produced by a combination of the reprecipitation and sonication method and termed the “ultrasonic method”. The TPClPP nanoparticles were stable in solution without precipitation for at l ast 30 days. No self-aggregation of the constituent porphyrin chromophores was confirmed. The TPClPP nanoparticles exhibited interesting optical properties; a large bathochromic shift in the absorption spectra.