UV (ArF and N 2 ) laser photolysis and IR laser photosensitized (SF 6 ) decomposition of gaseous secondary butene-2-ozonide (SBOZ) are shown to follow different reaction courses. ArF laser (193 nm) photolysis of SBOZ affords CO 2 , CH 3 OH, CH 3 CHO, CH 4 , HCOOH, CH 2 ᎐ ᎐ C᎐ ᎐ O and C 1 -C 4 hydrocarbons, while N 2 laser (337 nm) photolysis of SBOZ is a much slower process than SBOZ oligomerization occurring on the reactor walls. The multiple of the ArF laser induced photolytic products is in line with a complex reaction scheme involving initial O᎐O and 2,3 C᎐O bond splits of 1,2,4-trioxolane ring. Continuous-wave CO 2 laser photosensitized SBOZ decomposition affords CH 3 CHO and CH 3 COOH together with 1-hydroxylethyl acetate and 1-methoxyethyl formate, the products of rearrangement observed earlier in a pulsed CO 2 laser SF 6 photosensitized decomposition reported by us in a previous paper.