LDPE films were soaked into crosslinking byproducts which are acetophenone, α-methylstyrene and cumyl alcohol. The samples were used to perform the breakdown test. The ac breakdown measurements were conducted at a ramp rate of 50V/s at room temperature. Weibull plot is used to analyze the ac breakdown result. Comparing the soaked and un-soaked samples, it does show a small change in the characteristic breakdown strength as the LDPE film were soaked into the sample depending on the byproducts. It suggests that the breakdown strength is modified by adding the byproducts in the LDPE film. However, as the range of breakdown strength of all samples are to be compared, these values fall in the same region which indicate no significant difference can be seen in the samples. AC Pulsed Electroacoustic (PEA) technique was used to measure space charge in the samples. The result obtained from this test is used to explain the breakdown phenomena in the crosslinking byproduct soaked LDPE and space charge characteristics.