A　new　series　of　unsubstituted　and　halogenated　silicon(IV)　phthalocyanines　with　two　axial　poly(ethylene　glycol)　(PEG)　chains　having　an　average　molecular　weight　of　550　or　750　(PEG550　or　PEG750)　have　been　synthesised　by　treating　the　corresponding　silicon　phthalocyanine　dichloride　with　PEG　methyl　ether　in　the　presence　of　NaH.　The　compounds　have　been　unambiguously　characterised　with　1H　NMR　and　MALDI-TOF　mass　spectrometry.　With　two　bulky　polymeric　substituents,　the　compounds　are　essentially　non-aggregated　in　common　organic　solvents.　The　longer　PEG　750　chain　enhances　the　hydrophilicity　of　the　phthalocyanine　ring　and　is　more　effective　to　prevent　aggregation　and　fluorescence　quenching　by　Cu(OAc)2.　Substitution　with　heavier　halogen　atoms　on　the　periphery　of　the　ring　leads　to　a　reduction　in　fluorescence　emission　and　an　increase　in　singlet　oxygen　quantum　yield,　as　a　result　of　heavy　atom　effect.　The　compounds　Si(PcX8)(PEG750)2　[X　=　H　(4b),　Cl　(4c),　Br　(4d)]　are　photocytotoxic　towards　HepG2　human　hepatocarcinoma　cells　and　J774　mouse　mammary　tumour　cells.　Although　halogenation　results　in　an　increase　in　singlet　oxygen　quantum　yield,　the　general　photocytotoxicity　follows　the　order　4b　>　4d　>　4c.　This　can　be　attributed　to　the　opposite　effect　of　aggregation,　which　follows　the　order　4a　<　4b　<　4c　in　the　growth　medium.　The　interactions　of　4b-d　with　bovine　serum　albumin　(BSA)　have　also　been　investigated　by　a　fluorescence　quenching　method　and　a　non-covalent　conjugate　of　4b　and　BSA　has　been　prepared.　Conjugation　with　BSA　leads　to　a　higher　photocytotoxicity　against　J774　cells,　which　have　a　BSA-loving　macrophage　origin.