A polymerization process, the process comprising: contacting a catalyst composition with at least one monomer under polymerization conditions to produce a polymer, wherein the catalyst composition comprises a contact product of at least one organometal compound, at least one organoaluminum compound, and at least one treated solid oxide compound, wherein the at least one organometal compound has the following general formula: (X 1)(X 2)(X 3)(X 4)M 1 wherein M 1 is titanium, zirconium, or hafnium; wherein (X 1) is independently a cyclopentadienyl, an indenyl, a fluorenyl, a substituted cyclopentadienyl, a substituted indenyl, or a substituted fluorenyl, and wherein each substituent on the substituted cyclopentadienyl, the substituted indenyl, or the substituted fluorenyl, independently is an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, or hydrogen; wherein (X 3) and (X 4) independently are a halide, an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, or an organometallic group; wherein (X 2) is a halide, an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, a cyclopentadienyl, an indenyl, a fluorenyl, a substituted cyclopentadienyl, a substituted indenyl, or a substituted fluorenyl, and wherein each substituent on the substituted cyclopentadienyl, the substituted indenyl, or the substituted fluorenyl, independently is an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, or hydrogen; and wherein (X 1) and (X 2) optionally are joined by a bridging group; wherein the at least one organoaluminum compound has the following general formula: Al(X 5) n (X 6) 3-n wherein (X 5) is a hydrocarbyl having from 1 to 20 carbon atoms; wherein (X 6) is a halide, a hydride, or an alkoxide; wherein "n" is a number from 1 to 3, inclusive; wherein there is an absence of aluminoxane and borate compounds, wherein the at least one treated solid oxide compound comprises a calcined contact product of at least one solid oxide compound and at least one electron-withdrawing anion source compound, wherein the solid oxide has been calcined in an ambient atmosphere at a temperature from 400°C to 800°C and a time in the range of 1 hour to 10 hours, and wherein the catalyst activity of the catalyst composition is greater than 100 grams of polyethylene per gram of treated solid oxide compound per hour. wherein M 1 is titanium, zirconium, or hafnium; wherein (X 1) is independently a cyclopentadienyl, an indenyl, a fluorenyl, a substituted cyclopentadienyl, a substituted indenyl, or a substituted fluorenyl, and wherein each substituent on the substituted cyclopentadienyl, the substituted indenyl, or the substituted fluorenyl, independently is an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, or hydrogen; wherein (X 3) and (X 4) independently are a halide, an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, or an organometallic group; wherein (X 2) is a halide, an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, a cyclopentadienyl, an indenyl, a fluorenyl, a substituted cyclopentadienyl, a substituted indenyl, or a substituted fluorenyl, and wherein each substituent on the substituted cyclopentadienyl, the substituted indenyl, or the substituted fluorenyl, independently is an aliphatic group, a cyclic group, a combination of aliphatic and cyclic groups, an organometallic group, or hydrogen; and wherein (X 1) and (X 2) optionally are joined by a bridging group; wherein the at least one organoaluminum compound has the following general formula: Al(X 5) n (X 6) 3-n wherein (X 5) is a hydrocarbyl having from 1 to 20 carbon atoms; wherein (X 6) is a halide, a hydride, or an alkoxide; wherein "n" is a number from 1 to 3, inclusive; wherein there is an absence of aluminoxane and borate compounds, wherein the at least one treated solid oxide compound comprises a calcined contact product of at least one solid oxide compound and at least one electron-withdrawing anion source compound, wherein the solid oxide has been calcined in an ambient atmosphere at a temperature from 400°C to 800°C and a time in the range of 1 hour to 10 hours, and wherein the catalyst activity of the catalyst composition is greater than 100 grams of polyethylene per gram of treated solid oxide compound per hour.